And - in addition to what Rex said -
1) If you find a local Clippard distributor you can likely get the valve for $11; and maybe whatever adaptors you need for free.
2) If you shop around at local welding supply places you might beat the price on the tank and regulator.
Be sure to line up your source of CO2. Some places will only exchange tanks. If so, no need to buy a brand new one and especially not an aluminum one. I get my CO2 from a fire extinguisher supply company.