I stumbled across this site looking at something for work. Ten pound bottles less than $100 delivered to your door. A simple regulator is $50. Sure beats a PowerTank from Marlin for $440 plus the ride. Ya, their kit includes a bunch of other stuff ... but for less than $200 you can at least get a bottle, regulator, and hose and have what you need to fill tires.
10 lb. Aluminum Co2 Tank | BeverageFactory.com
10 lb. Aluminum Co2 Tank | BeverageFactory.com