If you have a bike coop in your area they are a good source that is worth checking out. They typically sell bikes they have received as donations and refurbished.
If the one here is any indication they will have bikes ranging from decent quality clear up to high end customs and all at usually more than fair pricing.
The one here is usually more than happy to help get someone on a bike. I've bought 2 frames and a bunch of parts from it.
