Hmmm... I don't think that the $50 is going to the hacker. I think that is just the fee for GetHacker to connect the project owner with a developer.

See the 'get to work' bubble on the homepage: "Once a project owner decides to pick you for their project, we'll connect you both via e-mail. The GetHacker process is over, and you both can take it from there." which implies that once a match has been made, there may be further negotiation, but it won't be facilitated by GetHacker.