don't see y not...i got my fx5 used for $135 w/media. it was used for less than 6 month be4 i bought it, and it's been working w/o problems ever since. so about 1.5 yrs now~~
I got one of my XP's used and it works just as well as the other few new ones I have. If the equipment is quality and wasn't abused or messed with you shouldn't have any issue.
I am still using my dad's Magnum 350. It is 15+ years old...lol
I purchased a new one and the manufacturing/parts are identical still. Crazy....
Depending on the canister manufacture/company, I would say go for it. Make sure you can still order parts for it - if you cannot, do not purchase it, or you might be sol if something breaks/needs replacing.