I think you need more emphasis on the prizes, at least proper links to what they are or a description to help sell them. Maybe it should include portion of all the application fees which seem quite substantial considering the costs of the prize and mechanical turk fees.

I'm also not convinced by the explanation that mechanical turk would provide effective feedback to a startup. Even if the scoring system did tell them where to focus, there should be another round of the top 50 or so with actual experts providing much more detailed feedback.