PAMite is the best mite-killer, hands down. You're right to be going with it. In the meantime, you could do dish-soap soaks. Get a Rubbermaid that's big enough for your snake to stretch out in. You'll then squirt in a drop of dish liquid in (I used non-antibacterial Joy for this years ago.) and add-in water that's slightly warm to the touch but Not hot, about the same temperature as your snake's water dish water... Make it nice and sudsy with your hands..

Make the water deep enough to cover your snake's spine, but not so deep that he has to swimto keep his head above water. Put the snake in; put the lid on. Leave for maybe about 10 minutes; keep an eye on him to watch out fo struggling and to prevent drowning, Take snake out.. you should see some dead mites floating in the water.. towel-dry snake and replace into tub. You can also do this while you're waiting for the PAM todry in the tub/tank when treating it.

I would skip the pet-store stuff; I don't know if it works, and I would be leary about using other chemicals/products in addition to the PAM. It seems overpriced to me as well.

I wish you luck in ridding your snakes of those horrible little things. I had them a few years ago, and PAM helped and worked wondes.