We get almost all of our servers from Nautilusnet. You can get a bare chassis for about $100. Of course, that really doesn't do you any good because you'd still have to buy a CPU (or two), RAM and drives. You can get two PIII 500MHz processors for ~ another $100, 512MB of Registered ECC for another $100, and then drives. Hmmm... $200 would be a real good deal.

Your best bet is getting a almost fully loaded used one off eBay because you end up spending less money in the long run.
I'd say jump on this, it even has 5 drives and array controller.