My favorite resource is the Shrimp Shack. I know the original one, now moved to Kingston Pike in Bearden, just east of Parker Brothers Hardware. They have their own trucks and fishermen on the Gulf and (I think) on the southern Atlantic.
The guys there are originally from the Gulf Coast and are wonderful people selling a quality product. IF they don't sell it, they turn it into gumbo and other great fish dishes that they then freeze and sell.