HI there!
You can get almost all of professional papers in 13x19, so you could print 1 12x12 layout and 2 6x6's at the bottom (or 3 4x6s). It's $35.99 for 20 sheets at Atlex. Here's the link to the Premium Glossy Photo Paper:
http://www.atlex.com/epson-paper/pre...ossy-photo.htm
Hope that helps,
Leigh