I'm in north MS, so it might be different down there. AirGas up here will not refill my CO2 tanks and neither will the one in Tuscaloosa. I did manage to find a store that deals with fire extinguisher refills and restaurant "automatic systems", so you might be able to find something similar down there. Could also hunt for a welding supply store. AirGas might fill them down there.
Ontap: Hard Cider
Primary: IIPA, All-Tythos IPA
On Deck: Munich Dunkel, Classic Rauch, Breakfast Porter, American Stout