Have you checked out Let's Swap it? It's a cool idea: a place where artists and designers can swap art for free. There is always one featured item up for swap (an edition of prints, etc). If you like what's up for grabs, you can submit what you'd like to trade (anything!), and the artist will choose the swaps they are interested in. I recently swapped with Mike Perry for this big, bright geometric print! Connecting with artists I like is always a total pleasure. Follow their twitter feed for updates on new swaps.