The Replay Sports store in McKinney is pretty strong. They have a solid selection, have discing employees but they sell an @ss-ton of used discs without calling the numbers in them... :|
I've talked to the owner about opening an East-side store but he says it's a no-go since he makes most of his mark-up on other sports' gear, and he claims the East side is mostly soccer players with very little profit margin.
There is a huge baseball/softball complex at Audubon, as well as 6-8 soccer fields and a waterpark if you are looking beyond just discs.