Invalidate this startup idea - 500 dollar prototype

I had an idea based on my many conversations with non techies with web or mobile app based ideas. It seems they always spend way too much on building their idea from scratch, even if they use offshore resources OR they forgo it completely as it is too hard to manage.

I've lost track of the amount of times I've put palm to forehead when I listen to a non-techie tell me how they spent thousands building their idea from scratch, when they could have used using that was already build - like a wordpress plugin, a rails or django clone with some extra work, or goodness knows what else. But they never even thought to ask around about other avenues.

So here is the idea - A proposer (a non techie type) posts their idea, and a bunch of technically savvy hacker news types propose ways to build the prototype for 500 or less, and people up/down vote stuff like stackexchange. Perhaps use crowdsourcing for others to up/down vote the proposals. The winning proposal wins and builds it for 500, minus a nominal fee that goes to the company.

The proposer can always continue using the builder of the prototype after the prototype is built, or they could take it to someone else. And 500 bucks is not chump change but it isn't a huge investment on the part of the proposer.

Just upvote this post if you would consider putting your hat in the ring to build a prototype for $500, or at least vote in other proposals.