You should set up a GW shop on http://www.cafepress.com . I would totally buy a shirt or two. That would help with lowering shipping prices and such (I think). 
way to not read the other replies to this topic.
OK, I just checked out
www.customink.com and I tried out the pricing possibilities. I had no idea that there was such a difference in price between 4 colors and 1 color, for example.
If we order 10 Champion Tagless T's with a design with 1 color on the front and 1 on the back, the price is $15.84 per shirt, shipping INCLUDED to the US (and Canada, I believe).
20 shirts would cost $10.97 each (again, same shipping situation)
If the shirt had only one color on one side and nothing on the back, it would be $13.35 each for 10 shirts and $9.01 each for 20 shirts
BTW this is all for a Denim blue color shirt. White is obviously cheaper, and there are many other colors available for these same prices