You could also seek a partner to finance the development, instead of limiting yourself to developers.
In my experience - there are a lot of great ideas. But turning the idea into a reality is the real challenge. If you found someone who was excited about your idea, had the skills to actually make it a reality, and was willing to do it for free - why would they still need you?
As a PHP/MySQL developer myself, I've had countless people in a similar situation come to me for help. Of the many ideas I'm approached with, scarce few are worth investing in because the fact is everyone has a "great idea" these days! Most of them are just a hunch or intuition with no compelling data to substantiate expectations.
Not being sour - just something to consider from their point of view; hopefully you have a lot to contribute to actualizing the idea as well. An idea is just an idea. I've got lots of great ideas. World peace is a great idea - fat chance finding a partner to implement it for me on a 50/50 split. :D