JEEZ! If I was as "out of the loop" as you guys, I would have to sell my junk. An hour's drive to get my bottle refilled? Driving An hour in Birmingham gets you to Montgomery. Call Airgas,...( or whoever does your welding gas exchange) and get an exchange acct set up for a 50 LB bottle of industrial grade N2O. If you don't have a truck for the monthly (or less) trip to have the 50lb er exchanged, get your buddies or Uncle Ernies truck instead.
Then go to a salvage/used appliance dealer and get a little upright freezer. On your way back from Crazy Elmos' Used appliances, stop off at Walmart, or Office depot and get a freight scale rated for at least 25 lbs. Get a 10' long -4 line for the 50lb Master bottle and you got your very own N20 refill station.....................................In Your Garage.
(Hopefully it's closer than 45 miles)