It's a hydrotest that has to be done every 5 years, not every year. I got an empty 15# tank on eBay for $67 shipped. Filled it for ~$13. $80 filled.Honestly those are really nice but the shipping and if you wanted them full is just too much. If you go to your local welding supply store you get a full 5lb tank for like $80. The think you need to know is you need to get a certificate of safety every year. So if you get it from a welding supply place you just bring your tank back empty then they give you a new full one. You won't have to wait to get it filled.
It's a hydrotest that has to be done every 5 years, not every year.