Some days ago I stumble upon this nice website called
It's very Etsy-like, but it deals only with downloadable art (not printable stationery or scrapbooking sheets).
You can upload your piece, set your price and start selling!
Your customers will purchase, download and print it.
The website is brand new, so it needs some word of mouth to get to be known.
Take a look at my Canvz page:
And here is my daily drawing.