rogerd - 3:30 pm on Apr 4, 2011 (gmt 0)
I'd use an established site like vWorker (formerly Rentacoder) or eLance to get quotes. Eliminate all coders who don't have a near-perfect satisfaction record or who haven't been on the site for at least a year or two. Then, look at the past projects of who's left and eliminate anyone who hasn't worked on projects like yours. (Sometimes, you'll find a coder with strong ratings has achieved them via really small projects; not good if you have a bigger project.) Once you are down to a small number of well-qualified coders, look at their responses (many are rote automation) and see if they really read your spec. Communicate more with the ones that look good - ask for an example of a similar project. Then, make a decision. If you hold to your standards, you'll have a very high probability of success on your first try.