I've been looking for such a product/project but I don't think it'll be easy to find such a thing. The process from $0 to $x where x > 1 is the most challenging part. x -> x * 2 is much easier as going from 0 to any number, you are essentially breaking the PMF barrier. Someone who did that probably understands business enough to be able to monetize the project into profitability or sell this baby at significant premiums (ie: 5 figures or more).

Most of what I found on Flippa and other markets:

1. AI drivels.

2. Suspicious customers. (ie: probably fraud).

3. Hype driven.

4. Real customers but more like consulting than SaaS.

5. Insane premiums for the value.

I've shot you an email.