Buy Propane (Green Gas) at Canadian Tire for $3.50/tank.
Buy Duster (HFC143a) at Grand & Toy for $12.50/can.
Buy an adaptor for both gases and a bottle of silicon oil from ASC Armoury.
"All of your questions have been asked and answered, and are easily available to you by simply using the "Search" Function near the top of the page." ...or something like that...
"And that's how, with a few minor modifications, you can turn one ordinary gun, into five guns." - Moe Sizlack