I don't think it is a good idea. If people want prints then they have to pay for the ink in their printers. If they print it out at home, then chances are that the printed vresion will not meet/match the high resolution that your file iis in. If this is the case, then people could just print it out at the quality which is poted on here already. If somone wants a good quality print and take the file to say kinkos or something, then they have to pay the ridiculous price they charge on top of what you charge (I don't actually know what kinkos charges for high quality color prints on good paper, but I know they charge around $11 to scan an 11 x 14 pic and convert it to jpg.). I think it would be cheaper, less hasle, and present the best product if the artist made some good prints and sold them. I know you may not have the money for that, but I think it is the best idea. Just my objective opinion. Doing good with the shirts, so keep that up!
Yeah Jay (Zombie) was thinking of doing it, and I was thinking about it myself, but I'm a little wary about it just based on already getting my art bitten pretty bad. I can actually get prints done fairly inexpensive, and I would probably do it case by case... It was just an option to make things more accessible. But I can see this going sour pretty fast.