I'm gradually making some of my better portrait miniatures available as postcards, greeting cards and phone cases over at Redbubble. Not alot of point enlarging them for bigger prints as they wouldn't really work, but these will reproduce them at their original size. If there was one you'd particularly like to be able to buy, get in touch and I'll upload a design. Here's one of my Daenerys efforts as an example. Don't know why I didn't think of doing this ages ago!
I'll have to check what products they have here on DA that might be useable.