Where did your team order it's tshirts?

We are looking for a new place to order shirts from.
These are some of the things we would like but we are fine if some of this isn’t available:
We would like to supply a .ai file or equivelent for our design
We would like some custom sizing options
We are also looking for a more durable fabric.

Ours are done at a local shop that matches the price of some of the larger companies. A few years ago we had a student design the shirts and submitted the design files. Since then, we have just given the shop an updated list of sponsors for the back of the shirt. Ours are just a standard cotton t-shirt but I am sure if you inquire you could order a heavier material (for a price). Be sure to ask for special pricing, they may be able to cut you a deal in exchange for a logo on the shirt.