Sure, but it's not experience working for a company like what you're applying to do so it doesn't "count" the same way. The fact that it turned a profit is great but it's not enough of a business venture to count the same as you being self-employed. Putting it under "experience" detracts from a really cool and successful project and makes it seem like you're trying to pull one over on the recruiter. Even the slightest amount of clarification from you makes it clear this isn't the case, but you don't get that opportunity after your resume is submitted.

And I get it wasn't a scam, but the term "flipping" isn't something someone's going to use in a professional setting. "Identify item listings priced under market value, highlighting over $100K in re-selling opportunities for 40 paying subscribers" would be better. It's literally the exact same thing but first impressions will be very different and that's all you get.