If you follow that advice, make sure that you don't make the mistake of thinking that you can build the real service on top of whatever the guy from craigslist throws together.
I don't think you'll have much luck unless you can find one or more coders who're as excited about your idea as you are, and who you respect enough to treat as equals.
I've seen a few friends take coding jobs like the one you're planning to fill, and while they got their pay, the people who hired them never truly got what they wanted.
it seems people have a lot to say about this, which is great. i'll probly put up a standalone discussion thread in a bit.
we understand it's going to be damn near impossible to find someone to make a perfect, usable product. that's not what we want.
we want someone to build us an ugly, barely functioning beta, just enough to get a few users on, in closed beta, to prove that it works and such. we just want a demo.
we're laying everything out in this program called conceptdraw, hoping we can give that document to a developer and be like "see, this is what we want."
that's a great suggestion though, we might end up having to do that.