First, look used. There's a bike swap in Springfield, VA on Sept. 26. Make a list of what you need, sizes etc. and go there. You'll probably be able to get most of what you need and for cheap. Details here.

Next, check the local bike shop, root through their boxes. If you are looking for cheap and functional and don't care about the latest and greatest, this will turn up some deals.

If you need anything else, scour aebike.com and you should be able to get some good deals on parts or at least an idea of what you need. For instance, if you need a decent set of working man's (woman's) cranks, these can't be beat. For chainrings, check Danscomp.com for their Universal ring.