When selling at art fairs it's best to stick to standard frame sizes, e.g. 8x10, 11x14,16x20 etc. this allows the buyer to get a stock frame, nearly anywhere and stick a photo in, rather than having to pay a framing shop an exorbitant amount. Clearbags.com is usually the way to go. Frame destination also sell clearbags, and I think they are slightly cheaper. The exception is very odd sizes, e.g. Panoramas. Such as this. I started off selling this only framed, but I'm now selling a lot unframed as well. The unframed ones are also unmatted, but I have them packed with foam core for support.