I used to own an incentive site. They do have potential - or at least used to.
Not sure about how that market is these days, since I'm no longer active in it.
I will say something on the subject of selling any type of website, though. Nobody will pay for potential. Potential in itself is not how a price of something is determined. You would need to show us that you have active members completing offers, or something of that nature. Otherwise, the site is no where near as valuable as you're claiming it to be. Just my $0.02.
So, if you have any proof of income, post it here. Otherwise, would you consider a much lower sale price?