Well, around here there's Asheville Aquarium/Java Reef (coffee shop inside a LFS). They tend to have more saltwater selection than fresh, but also have a decent amount of pond supplies (which can be used for very big tanks as well). They have a 500 gallon acrylic tank along with many other good-sized display tanks for both fresh and salt. Although those tanks don't seem to be for sale, I know they take orders for custom tanks for both glass and acrylic. I think they do have a used 300 acrylic for sale...I just haven't asked how much they want for it yet.
If you don't mind doing a good quarantine and want some more rare fish, WNC Aquariums specializes in hard to find stuff. Their staff sucks though, and they don't keep the place well.
Both Petsmart and Pet Supermarket keep their fish well here. Petco sucks though.
The next time I head over to Greensboro, or up to Cherokee, I intend on checking out a couple of places, but I haven't done too much shopping outside of Asheville.
As a side note, I have some friends that are into fishing that I'd be happy to ask where to go whenever you come this way.