If you have all your artwork then Zazzle is a good place. You can set up a store and then "sell" to yourself and your teammates by the piece. No set up fees. Just a price by shirt. This past weekend they had a 40% off tshirt sale and I bought a bunch of full color shirts (back and front print) for 16.73 each with $4.00 in royalties coming back to the team from my team store.
Math - Full color shirts, no minimium, $12.73 a piece with free shipping. Can't beat it with a stick.