I recently started an account on Imagekind. I love how easy and flexible the site is for buyers and sellers, alike. It also makes me feel good to see some illustrations I really love available for others to enjoy, especially since I've taken many off of my streamlined portfolio. It's also a nice way for artists to get prints made for themselves (or family!).
I'm considering making a few pieces available just for selling, and currently this is the only place to buy my work as a print.