I just bought two 125 cf tanks from Airgas for $164.00 each, and the 80 cf were around $159.00. So it was a no brainer on which to buy. I bought others in the past as well and have never had a problem exchanging them. But it wouldn't hurt to keep the receipt in case they ever ask for it. You may check around, and get a better price from someone in your area, make sure to check prices on the different sizes, the larger one may only be just a little more. Hope this helps.