My big king, wild caught and quite healthy (though I've not had funds to take him to the vet check for internal parasites and the basic rundown), just got mites from a new substrate of all things. It was T-Rex coconut bark that I got at petco (though the mites could have been on the outside of the bag, either way when I went to a better quality reptile store and got a free sample of the stuff it was clean, no problems). So I searched the forums high and low and have made a list of things I would get and use for treatment.
1. Prevent a Mite : Read instructions and use as instructed, am definately not out to kill my snake. But dependant on price.
2. Sevin Dust (5%) : Got this from a thread on Burmese pythons, was going to line outside of his cage and put the other cages on cookie sheets with the dust in the sheet so mites don't get spread to them. If Prevent a Mite is too expensive I would use this on the snake and cage, typically for the snake my rubbing it on him. The thread stated teh obvious of not the mouth of nose, but said eyes were alright because mites infest the area, I will wait to see if anyone here is qualified to shed some light on that. Until then I'll do the entire body but the head.
3. Mineral Oil : Strictly optional, last resort sort of trying all my cards deal. Am not going to get this to use in conjunction with the sevin dust because I think it would just make a big mess and just be overkill.
Anyway, I'll post up some pictures of the entire collection so far later tonight. 
