I've been making postcards for my next show. 600 (for now) hand screened, multicolored on index cards from Office Dept - each one has my sweat and dirt on them. Smell them if one happens to fall in your lap.
I like making postcards this way. It makes the cards less about the project and more a part of the project. People get excited to receive them.
Maybe people will start collecting them, far away in the future and they will only be a few left and they'll fetch high prices at auction. Think about that, people paying hundreds for an index card, transformed!