I would think the possibility of maximizing your revenues to levels most full-time employees can only dream of would be enough of a reward. But what do I know? You're the guy who's surrounded by these guys all the time, you probably have a better idea than I do what makes them tick.
By the way, I'm really glad you're doing something you would do for free. That's how you know you're on the right path! Just...don't tell too many people, they'll try and take advantage of you. Trust me on this one