6 Unsaturated Business Ideas From a Founder Who Started 75 Companies

Everyone is building the same AI wrapper right now.

Meanwhile, half a billion people shop on Facebook Marketplace every month and almost nobody has built real tools for them.

That gap is the whole point of this story. Chris Koerner (he says he has started 75 businesses, with 10 of them reaching 7 or 8 figures) sat down with Greg Isenberg and walked through six unsaturated business ideas he would start today. Not one of them is a ChatGPT wrapper. Most of them cost a few hundred bucks to test.

I pulled the real numbers out of the episode so you can steal the playbooks. Watch the full conversation here:

1. Third-Party Apps for Facebook Marketplace

Chris opened by reading stats at Greg like a prosecutor.

Facebook has over 3 billion monthly active users. Around 16% of them use Marketplace every month. Half a billion people. And per Chris, 51% of recent social media purchases happen on Facebook Marketplace.

Now the weird part: there is basically no third-party app ecosystem on top of it.

Compare that to the neighbors. eBay has thousands of apps built on top of it, and some of those got acquired for hundreds of millions. Shopify's app store has around 12,000 apps powering 87% of merchant stores, and developers have earned about a billion dollars through it (roughly $100K per year for the average developer on the platform).

Facebook Marketplace? Chris found "a couple kind of janky ones." Nothing legitimate.

He even tested the obvious objection. He vibe coded his own Marketplace app that scanned items and reached out to sellers, without knowing how to code. It worked. The API permissions allow it.

Some obvious wedges:

• Price alert apps for people who make their living flipping on Marketplace
• Arbitrage tools ("this dresser is listed at $80 here, sells for $240 on eBay")
• Auto-posting and auto-responding tools for sellers running at volume

Chris told a story about posting a video on appliance rentals. A viewer started listing appliances for rent in other cities, selling the leads to local operators, and vibe coded his own internal app to post and respond automatically.

→ People are already doing this in the shadows. Nobody has productized it. That is usually the signal.

2. The "Dumb Product" Studio

Chris's favorite quote: first-time founders focus on product, second-time founders focus on distribution.

His example is a round piece of foam. You wrap it around a boat propeller when you are parked so kids don't cut their legs swimming near it. Nothing proprietary. Nothing clever. They sell thousands of them, because the 10-second demo video keeps going viral.

Half the comments call the product stupid. The algorithm reads that as engagement and pushes it harder. The other half of viewers buy one.

So the business is not the foam. The business is a product studio built on three tools:

• AI to generate hundreds of "dumb" product concepts
• A 3D printer to prototype them for almost nothing
• Short-form video to test demand before you spend real money

You only order inventory when a video pops and preorders come in. A Shopify page and a waitlist is the whole validation stack.

Greg added a twist I loved: people on TikTok actively hate AI right now, so put one deliberately pointless AI feature in the product. A voice-enabled propeller guard. The comment section fights about it, the algorithm feeds on the fight, and the buyers show up anyway. Rage-bait as distribution.

3. Mobile Bike Washing at $800 a Day

This one is boring, sweaty, and my favorite kind of idea.

Cyclists spend $5,000 to $15,000 on their bikes. Washing one properly takes an hour, needs a hose and degreasers, and most riders live in apartments. So they either skip it or pay a bike shop and wait a week.

The play from the video: an automated bike wash on a trailer, parked at trailheads, bike parks, and races. $20 for a five-minute wash and dry. 40 washes a day is $800 in revenue. No inventory, no employees on day one.

And you don't start by buying anything. Chris was blunt: the box trailers cost around $10K, so don't. Rent a trailer, buy a $200 pressure washer, and wash dirty bikes by hand at the spots where dirty bikes already are. Prove people pay. Then upgrade.

The scale layer is subscriptions. Greg's friend owns car washes and makes most of his revenue from a $40/month unlimited plan (members only come once or twice a month anyway). Same logic here: $25/month for unlimited washes, sold to the riders you already see every weekend.

Greg's distribution angle: cities operate long bike paths with rest stations. Sell a dozen machines to the city, split the revenue, collect a maintenance fee. Less per day, far more passive.

→ Start manual, prove demand, then buy infrastructure. Same arc as the boring businesses that quietly print money.

4. Anti-Spike Stickers for Bars

A sticker you put over your drink at a bar so nobody can slip anything into it.

No sensors, no color-changing chemistry, no app. A sticker.

The unit economics are silly. Stickers cost about a cent and a half each. A roll of 1,000 might cost you $25 to $30 printed. Chris figures you sell it for $100 to $200 a roll, in cases, on a monthly subscription.

The pitch to the bar basically writes itself: you get to be the safest bar in town, it costs you almost nothing, and honestly it is a liability not to stock these.

Distribution is the part most people would fumble. Chris's plan: scrape every bar in your area, send each one enough free samples for a busy night, then follow up until they land on the subscription. That follow-up sequence is the actual business (a solid lead nurturing strategy matters more here than the sticker itself).

He has run this exact motion before. In 2010 his iPhone repair store in Tuscaloosa was dying. One sleepless Sunday night he ordered custom Tyvek wristbands for 2 cents each, walked into bars at 3pm and asked, "do you give out wristbands? Want to give out mine instead, for free?" Students got drunk, broke their phones, woke up wearing a wristband that said 15% off iPhone repair.

That one idea changed the trajectory of the whole company.

And the bonus layer: make the default sticker carry your brand and QR code. Plain ones cost the bar extra. Custom-branded ones cost more than that. Every drink in the bar becomes your ad.

5. Shiny Rock Vending Machines

Rocks cost 5 to 20 cents. Kids pay $2 for them. A 90% margin on a product that never expires and never attracts bugs.

Put the machine at a trailhead, collect cash weekly, refill with rocks.

Sounds like a joke until Chris brought up Buc-ee's. Their store layouts are ruthlessly optimized per square foot (it is why there is nowhere to sit), and they still dedicate floor space to a shiny rock station where kids fill a $25 leather bag. If it survived Buc-ee's spreadsheet, it crushes.

Greg's variant: seashell vending machines at airports and beach-town restaurants, for the kid who flew home from Miami without finding a good shell.

The deeper point from Chris: vending machines are offline A/B tests. Same machine, swap the product and signage monthly, learn what sells where. Cheap experiments, physical distribution.

6. Corner the Market on "Lame" Pokemon Cards

The weirdest idea came with a reveal Chris said he had never shared anywhere.

Backstory first. An anonymous collector known as the Kabuto King started buying every first edition Kabuto card from the 1999 fossil set. They were worth 30 to 50 cents ungraded. He tweeted about it, turned a lame card into a meme, and the price ran to $10 to $20. Over 100x in about three months, per Chris, with graded copies worth hundreds.

Chris copied the trade. On the episode he held up stacks of first edition Shellder and Krabby cards: around 1,700 of them, bought on eBay and TCGplayer at roughly $2 each including shipping, about $3,500 total. He had told nobody what he was buying until that moment.

The mechanics that make it work:

• Supply is fixed. Nobody is printing 1999 first editions again.
• 2 to 5% of cards are misprints worth $20 instead of 20 cents. Cull them.
• Mint copies cost $15 to grade and come back worth $100. Flip those to recoup your cost.

His eight-figure version: hire someone at $50K a year to buy every first edition card on the market, all 152 characters, skipping the famous ones. Roughly $400K to own most of the floating supply. Anyone who ever wants a full first edition set has to come through you.

The idea behind the idea is even better: grading itself is broken. PSA charges $40 to $50 per card and makes you wait three or four weeks. Chris and Greg workshopped the disruptor live: $5 grading from iPhone photos, AI scoring the card like a bank scanning a check, graded live on stream like Antiques Roadshow, shipped back in packaging that actually looks good.

Somebody listening will build that one.

What These Six Ideas Have in Common

None of this is about rocks or stickers or Krabby cards.

Chris looks for one pattern: a market where demand is already huge but the tooling is primitive. Half a billion Marketplace shoppers with no apps. Collectibles with one slow, expensive grading monopoly. Thousands of filthy $10K bikes and nobody at the trailhead.

Then he starts embarrassingly small. A rented trailer before a $10K rig. Free samples before a sales team. 1,700 cards at $2 before a $400K market corner.

When someone asked him on the episode whether these things are even scalable, his answer stuck with me: everything is scalable. The only real question is how hard it would be to scale to your number. For some founders $100K a year is the number. For others it is $10 million.

I see the same pattern in every founder I interview who found an underserved market: they didn't invent demand, they found it sitting in the open and built the missing layer on top.

Pick the idea that matches your background. Then, as Chris put it, get out of your seat.

FAQ

What is an unsaturated business idea?

An unsaturated business idea targets a market with proven demand but few serious competitors. Facebook Marketplace is the textbook case from this episode: half a billion monthly shoppers, yet almost no third-party seller tools exist, while eBay and Shopify support thousands of profitable apps.

How much money do you need to start these ideas?

Less than you think. The bike wash starts with a rented trailer and a $200 pressure washer. The sticker business starts with $25 to $30 rolls of printed stickers. Chris Koerner's Pokemon position cost him about $3,500. Only the full card-market corner ($400K) needs real capital, and he suggests funding it by grading and flipping mint cards along the way.

Who is Chris Koerner?

Chris Koerner is a Texas-based entrepreneur who says he has started 75 businesses, with 10 reaching 7 or 8 figures, across repair shops, e-commerce, and services. He runs the holding company Cofounders and hosts The Koerner Office podcast, where he breaks down business ideas like the six in this episode.

Are vending machines actually passive income?

Mostly no, and Chris and Greg say so directly. You still collect cash, refill product, and maintain machines. Their framing is that some income is more passive than others. The shiny rock machine gets close because the product costs 5 to 20 cents, sells for $2, and never expires.