No one mentioned a LDS that does both internet sales and walk in.
I'm in no way affiliated with them, but they're nice people and I would like to give them a plug.
Divers Supply:
http://www.divers-supply.com
I go to the store in Macon. There are several stores, in Fla, SC, and GA. 9 locations plus the internet.
That's the way I see to make it worthwhile, consolidate with other dive stores, make big volume purchases for each store plus a central warehouse.
I've bought several tanks there at reasonable prices, even cheaper than mail order (no shipping charge).
BTW: I have my own compressor, a little gas or electric portable, it's extremely convenient to be able to get air anywhere I go, but... I'll have to fill 400 tanks before I break even.
I hope this wasn't a taboo, advertizing for a shop, I just felt it relevant to the topic.
Cheers,
Warren