Yeah, if they found more, it was off-screen. Not to say they couldn't have grabbed ammo off of any of the giant group of dead soldiers around the CDC, though. That should have set them up for life, as every one of them would have had machine/hand guns and ammo on them, although they might have to add some together to combine clips and whatnot.
Also could have found stuff in the traffic jam easily enough, they had forever to look...
Living here in the greater Atlanta area there must be a Wal*Mart store every 5 miles - even in rural communities. The production costs related to recreating that enviornment was probably not cost effective nor likely would Wal*Mart want to lend there name to a zombie flick [or maybe so?
] but it's surprising that type of store wasn't used as a re-supply location.
Any Wal*Mart store could have supplied the group with everything for life.