I don't think they really have many vendors at the gunshows (at the Civic Center). I buy most of my Glocks from Southland Gun Works. The guys there are friendly, and for the size of the store, they have a pretty good selection. It is across from the Darlington Race Track (the large track, not the dragstrip).
I am not sure if you are familiar with Wadesboro, NC but I would recommend Village Pawn and Gun. It is a pawn shop but has more guns than several gunstores I have visited. They have a huge selection, considering the size of the place. Sometimes, you may not find what you are looking for out front but they may have it in back.
They carry most/if not all model Glocks, many of the Smith N Wesson revolvers, Sigs, Springfield, Ruger, Mossberg, Remington lines of guns and more.