I wonder if there is an (inexpensive) service where people would be given free reign on a dev site? If not, I imagine one could be made kind of like rent-a-code

I wonder if there is an (inexpensive) service where people would be given free reign on a dev site? If not, I imagine one could be made kind of like rent-a-coder: every time a user found an exploit, the site owner would give them karma for credibility and a commission fee.