If you make it back to Pittsburgh you need to go to Baseball Card Castle in Cranberry just outside the city. Jeff the owner there is a great guy and he has a tony of stuff to look at and buy. Sports Card Junction would be #2 and they are more south of the city. I go once in a while to SportsCards Etc, but usually only buy what might be on sale.
Jeff in Cranberry is the best place for hockey, and he has ton in the back as well. He can get super busy there but he does his best.