My experience in buying bottles off of craigslist, etc... has been just go buy it from the welding store. People don't sell used bottles that the inspection is up to date on.
-Karl
2006 Chevy K3500 4X4 - No J.B. Weld on it yet!
1982 thru 94 F-Series "The Klogger" AKA Transport on the road, on the trail, or on the trailer!
1965 Chevelle
1975 Corvette