Im running a paintball tank setup , my 20oz tanks cost 3$ to fill at the pball place.
there is no gas supply shops in town here , so every few months i travel out and get my 20lb tank filled, then i have a paintball tank fill station , just flip the tank upside down and fill my own pball tanks for the kegorator and for playing paintball.
works well , if your into playing paintball and drinking homebrew... "2 birds one stone".
cheap too . cost between 17-22$ or so to fill the 20 lb talk... at the welding shop's around here.
filling them myself the 20oz tanks cost around 1$ to fill