Yeah, that’s a lot of work. Heck, I handled tees for a simple group trip recently and it was a big pain.
Another bike specific forum that I’m on started a webstore on Café Press for tees and other gizmos (e.g. coffee cups, mouse pads); one of those on demand, turn-key outfits that handles everything. IIRC they don’t royalty back to the site owner, though. The items I purchased were of very good quality. I think there are other offerings on the web similar to this. It's probably one of, I'm sure, many alternatives to consider. Here's the store to take a peek at...
http://www.cafepress.com/XR1200