My buddy made his own from a 20lb CO2 bottle used for soda's.
He bought everything off ebay for less than 100 bucks.
There are a lot of write ups on the web about what to get and where.
My rig... "Maude"
1976 FJ40 with some stuff and some leaks.
1999 UZJ 100 Series bone stock ready to rock AKA:The backup minivan
2012 Toyota Sienna Minivan, fastest Toyota in the stable.
My camping trailer build up thread.
"You 80 guys are just a Sawzall away from nirvana." -Red Chili