I mentioned a few weeks ago that my dad is starting a new bbq business and wanted shirts made. After spending quite a long time searching for the cheapest tshirt printing place, I came across ooShirts.
Fantastic. I can't stress enough how great they were to work with.
They have someone review your design (for free!) before you submit it. How great is that?
They also include shipping right into your order price, and guarantee that it will be on your doorstep in two weeks.
Their prices are very reasonable and I'd highly recommend them! The more tshirts you'll be printing, the price goes down.