So I wound up buying a used aluminium tank ($10, gas to get there cost more) and it cost me $12 for VIP. Looked on outside. OK. Screwed top off, dropped xmas tree lights on inside and looked on inside. OK. Cost plus refill of air was $12.
It's for an airgun and if you belong to the National Muzzle Loading Rifle Association, you'll see my article on it in the Jan 2023 issue.