I just had 50 shirts done by a local shop. There wasn't enough savings on an internet purchase to jack with it and hope what showed up was correct. Local guy formatted the design and had it ready in a couple days. I did 2-color front, back and sleeve for about $7.50 each, you can probably get a better price for a larger run.
I have used this place, they had free shipping but I always picked up. just get proofs before printing, they screwed up once on me, but took care of it.
also if your going to re do an order ask them for the artwork files back so you have them for the next time either thru them or someone else.