@Marie13 In your situation, why not just get banked nitrox. Banked nitrox does not need to go into oxygen cleaned tanks since you are not dealing with high % of oxygen. I hope and seeing that in the near future, more and more shops are offering banked nitrox. Recently I saw one offering 32, 34 and 36% banked nitrox, no cleaning required.
DRIS is the only shop I know of locally that banks. It also doesn't seem to be readily available when traveling. Remember - I'm diving the Great Lakes, not in Florida. And when I travel, I don't want to have to haul more than 2 tanks with me. The people I carpool with would not appreciate it, especially if they rent tanks at destination.
Also, I'm not going to limit myself to wrecks at 111ft or shallower.