I sort of just went through this myself. My 10# bottle is nearly a year past its 5 year stamp, but a liquor store in Tempe seems not to care, and fills it for $15. However, a welding shop told me I can get the tank re-cerfied at Thunderbird Cylinder.
Meanwhile, I'm thinking I'll get a new 20# bottle, and get the 10# re-certified once that's in place. Anyone know of the local prices on 20# aluminum bottles? This is best I've found online so far:
https://beveragelements.com/beverag...o2-cylinders/20-lb-co2-cylinder-aluminum-new/