Just an FYI that I have opened a t-shirt shop on Spreadshirt. It's a site that digitally prints artwork onto shirts. I bought a shirt, (pictured above), before opening the shop to make sure the quality was on the up and up, and I was pleased with the job they did. The result isn't as vivid as a silk screened shirt, but it's perfect for more detailed images.
The major drawback to this website however, is that they have strict "ethical" rules, and have rejected a number of my images due to nudity. I think this is ridiculous... they're just nipples for goodness sake! It's a bummer, because many of my designs will not be available because of this censorship.
Nevertheless, it's a pretty cool service, and you can check it out here. Maybe you can open your own shop!