I'm going to bring back all my capes but I may or may not get them all mounted right away.

What is the best way to have them prepared for storage? (should I have them tanned?)
What is the best way to store them?

Have them tanned and put them in a freezer. Even dry tan (I prefer wet tans for mounting) need to be frozen so as not allowing the chemical breakdowns that do happen in tannage. If you wait too long for an unfrozen tanned hide, it could fall to pieces when wet down for mounting. Personally, I'd have them wet tanned and they'd go on the bottom of my freezer until I was ready to mount them.

Agree with george %100. If you can't afford all the mounts now, that is by far your best option.

Thanks guys, will do.