I picked up a 21.5" 2011 iMac and a 27" 2011 iMac this year, both from the refurb store.
I'm a big fan of the refurb store. You get like new products and the same 1 year warranty. The only frustrating thing is that sometimes you have to wait until your particular model shows up. Refurb.me is a good site, but I can't seem to get their email updates to work either.