Hey now, folks... I never confirmed that the profit on a single tee shirt is $2. In retail of this type (gifts and souvenirs) the general markup equation is (cost X 2) = retail. Then we have to add in just a little bit to cover the freight costs, which can be pretty high these days. We buy our tees in fairly large volume (thousands every summer) so we can usually get a slightly better profit margin than (cost X 2). So... if the regular retail of a tee shirt (at the Summit gift shop) is $20.00, and the cost is about half that, then we might make around $10 on the average per shirt.
I'll check back later to see if there are any more guesses.