I had a problem with mites last month on a snake. I too tried the cheap stuff at the local pet store and it did nothing. Since I had to order PAM from the internet and wait a few days for it to come in, I decided to try something. I used dog shampoo that kills fleas/ticks. Since mites are related to ticks I figured that it would work on mites. Bingo, killed all the mites with one use! I used the seargents flea and tick shampoo for puppies with oatmeal, so it wasnt the full strength for adult dogs. Followed the directions as if I were shampooing a puppy, and it worked. No ill effects on the snake, and he is back to his old self and mite free! I treated my rack system with raid insect killer and let it stand for 4 or 5 days to air out before putting my snakes back in it. Havent seen a single mite since. So for about $8 I got rid of the mites in a single day.
There were still a few dead mites stuck to him after the shampoo, and the ones that didnt fall off, came off with his next shed.
If you decide to use this option, make sure you observe your snake for a few days after to make sure there are no more mites. You may want to put it on newspaper or paper towels so you can see any mites that are alive. Alive ones will be moving around, the dead ones that fall off the snake will not be moving and will be dried up.
Good luck and keep us posted.
-----
1.0 Corn snake "Warpath" (KY locale)
1.0 Black rat snake "Havok" (KY locale)
1.1 Black rat snakes "Punisher and Mystique" (MO locale)
1.0 Eastern Yellow Belly racer "Nightcrawler" (MO locale)
1.0 Albino Black rat snake "Malakai" (Dwight Good stock)
1.0 Everglades rat snake "Deadpool" (Dwight Good stock)
0.1 Greenish rat snake "Rogue" (Dwight Good stock)
1.1 California king snake "Bandit and Moonstar" (Coastal phase)
1.0 Prairie king snake "Bishop" (KY locale)
0.1 Black king snake "Domino" (KY locale)
0.0.1 Eastern Milk snake "Cable" (KY locale)
0.0.1 Eastern/Red milk intergrade "Omega Red" (KY locale)
Good luck and Happy Herping
Brian