If you live around Chicago, you might check out
http://www.surplusvillage.com .
I just picked up a refurbed 21" Dell D1626HT for $100 and it's in great shape. In fact I'm staring at it right now and it looks a lot better than the monitor that came with my PC. I ordered it on the web, and then picked it up at a loading doc by the north side of O'hare.