nhaler has some rev 5's. Health Cabin has some Rev 4's.
They're getting tough to find. Royal Smokers is difficult to do business with, I've read more than a couple of vendors say... and the clearomizers are more popular then the steel XLs. So, if you intend to use your MAP tanks for an extended period of time, I suggest you stock up when and where you can. Also, keep an eye on the classifieds. I see CE2s and MAP tanks or MAP tank parts fairly often.