threadbird.com does awesome printing. They used to be Storenvy printing when I've used them - but they've branched off just for printing now it looks like. But they are based out of the US. Maybe drop them a line.

BTW, I don't know if your startup is just a temporary t-shirt store, but here is my 2 cents from my brief experience selling shirts: Spend a little more for the better quality shirts, you will get repeat customers. I highly recommend the American Apparel shirts. It really does make a difference. Also, if customers know that the shirt is AA, they are definitely more likely to buy if you list it for a moderate price. The quality is far superior and in my opinion, just feel better wearing them.