I guess the concept is ultimately a 2-sided market of 'proposers' and 'builders', so the challenge would be balancing them effectively.
I think its unlikely you'd ever have a problem with too many builders and not enough ideas. I think the challenge will be attracting builders (i.e. developers) who are willing to build these prototypes.
As you've probably heard, developers are in high demand right now. A hacker worth his salt is probably charging at least $100/hr, so $500 for a prototype doesn't sound that attractive.
I think its unlikely you'd ever have a problem with too many builders and not enough ideas. I think the challenge will be attracting builders (i.e. developers) who are willing to build these prototypes.
As you've probably heard, developers are in high demand right now. A hacker worth his salt is probably charging at least $100/hr, so $500 for a prototype doesn't sound that attractive.