halocline
Contributor
There are two common brands of AL80 tanks available (luxfer and catalina) and they are slightly different but more-or-less the same. I would never purchase a new one. It's a waste of money considering that used tanks are perfectly good and often about half the cost. Shipping on tanks is expensive too. A surprisingly good option for many divers is to buy a used tank from a local shop's rental fleet. This helps avoid the occasional problems with getting tanks from a different source filled and inspected.
From what you've described, a LP72 sounds perfect for you, and you'll have to find one of those used. It should not cost more than $50.
The valve issue is simple; if you have a yoke regulator, get a yoke valve. If you have DIN, get a DIN tank. If you don't know the difference, do a search but I would suggest you start with a yoke regulator and tank. It's much more common in the U.S. and renting tanks will be simpler. There are theoretical advantages to the DIN system but none of these are nearly as important for recreational diving as is being able to connect your regulator to commonly available tanks.
