To break it down and make it easier...

If you were to order 50 Brown Slim-Fit Tees with a Cream print on the front
(like the tee pictured left) the cost would be as follows;

Now, if you were to resell the tees at shows, in stores, or from your website;

After covering the costs of the tees, you're left with $450! Not bad?! And it's not just about making money for your band - the real value is in getting your name out there and portraying a professional image to people in the industry, and your fans.