I'm working on piecing together a "PowerTank" CO2 system to use with my 4Runner and thought I'd share my trials and tribulations so future people can find the parts without having to search around and pay needless markups from resellers. Much of my own experience is based on his IH8MUD thread on the same subject: Build Your Own CO2 Tank System High Quality & Lowest Cost. In short, it's easy to build your own CO2 system for less than $200 if you kind of know what you're doing and aren't attached to a 100% name-brand-or-nothing metality. If you know EXACTLY what you're doing and have some air hose couplings already lying around, you can build the system for maybe $150 not including a mounting scheme (the IH8MUD thread suggests using a heavy duty fire extinguisher mount, I'm ratchet strapping for now).

I bought an aluminum 10lb CO2 tank from Beverage Factory: http://www.beveragefactory.com/draft...anks/co2.shtml

Their tanks are very nice and priced well, I got my 10lb tank for about $95 after shipping. I swapped it for a "loaner" tank from Matheson Tri-Gas and will be getting the nice one back on my next exchange (I'll probably "exchange" the loaner tank early just to get the nicer tank back). In retrospect, I probably just could have gotten a tank from Matheson directly with a core charge, but oh well. It all depends on whether you can find someplace that fills, or just exchanges.

The regulator is a much simpler problem to solve than most people think: you don't need an adjustable one, and you don't need a gauge, so a fixed-pressure welding regulator is the way to go! I bought mine from www.outbackequipped.com, only to find they are re-selling Western brand pre-set ones.

So my suggestion is get a Western RP320100 from someplace like here (100psi which means you can use tools with it if needed): www.weldingsupply.com. The regulator is $40 + shipping, which pisses me off considering Outback sells "theirs" for $60. Oh well live and learn...

The regulator has a 1/4" NPT threaded connection on it, so attach whatever hose connection you desire and you're good to go!

I also went ahead and bought a tank boot from Amazon: Power Tank TBT-6090 6.9" Diameter Tank Boot for 10 lb. and 15 lb. Tanks, only to find it isn't actually a PowerTank brand boot, but made by a company called Underwater Kinetics for SCUBA tanks. SO as with the regulator, all you need to do is buy the Underwater Kinetics one, and you'll save a few bucks over the same "Power Tank" one...

Everything said and done I'm about $180 in, which is a real steal compared to a name-brand system, so I'm very happy. Knowing what I know now I might have been able to get everything for around $150, so there's really no reason not to build-your-own system these days. Be sure to secure it well in the back, and you've got compressed CO2 on-hand at all times!