What I'd do, would be a limited run, with unique numbers on each (fx. on the back or as a very small number in a corner). That way, they represent a value as a collectable...I have made some poster designs that I sell copies of, for USD 80 á piece, and I'm not a known artist or anything. The posters cost 9 USD per print (high quality UV-protected), and they measure 39.4 x 70 cm, and the printing agency is two roads from where I liveI bet you could easily pull off at least USD 100 for your prints, probably more.