Nitrous plumbing A1A...??..

Doing a little research on the nitrous bottle.. a used one popped up on Craigslist with a bunch of accommodating parts..
So I called the place that fills bottles and ask them about certifications? they referred me to a place here in town that does the certifications.. it cost $40 and there's a 24-hour turnaround generally. The certification is for five years..
So I called the guy about his nitrous parts and the best he could find was a stamp that said something about 1999 LOL.. he said the bottle is full and he's had it for a couple years and it came in a car as part of a package deal and was not hooked up. so it looks like this has been full for a long time and been bounced around from person to person. Obviously I thanked him for his time and got off the phone.. likely I'll buy new but if a good deal comes along on a certified tank that's another story as well.. he also had some NOS solenoids which are a little bit more expensive than the Zex and I know you can buy rebuild kits for them..
Anyways I'm going to pass on the deal but still take it as some more good research...