Lately I started to create and sell ACEOs on eBay. ACEO stands for Art Cards, Editions and Originals. The only standard requirement for ACEO is that its height and width measurements be 2.5" x 3.5" (64 x 89 mm). Here are some ACEOs I've created.
If you'd like to purchase any of my paintings, just send me an email with the painting's title at the subject, and I'll get back to you with some more info.