If you have a few LWS dealers around you, it is best to do some shopping around for the best price on welding gasses.
I have found that one gas dealer charges a lot more than another. But they have better prices for consumables like tig rods, torch collets and such. But in order to keep the goodwill with the cheaper priced gas dealer, I buy my consumables from them also. In a pinch, I may buy from the other higher priced dealer but I want to reward the dealer with the cheaper gas as that is my highest cost for tig welding.
You will get a better deal on gas if you pick up yourself. Yes it is convenient to have the tanks delivered but you do pay for the delivery service.
As far as transport, the largest bottle I now have is a 300 cubic foot tank and it is 9 inches in diameter and 5 foot tall. It fits in my little 1991 Honda CRX HF with the passenger seat folded down. It weighs around 180 lbs and it a bear to lift. But I don't have to buy gas every other week as I did with the 150 cubic foot tanks.
I also have a spare 150 tank just in case I run out on the weekend. Why is it that the gas always runs out on Saturday or Sunday?
Powertig 250EX
Powerplasma 50
Hobart Handler 210 with spoolgun
Cobra 2000 / Henrob O/A torch
Drill press / metal brake / 36 ton air hydraulic press
Franzinated modified Craftsman 33 compressor
Lots of other metal working tools