Update: I purchased PAM two days ago and treated my setups. This was done just to prevent any possible contamination, not only from the infected snakes but from different reptile shops I go to . Better safe than sorry. After I was done I went to the person's house and treated his enclosures, he couldn't afford to buy PAM. This was almost three days ago. Today I went by to see how things were going and I couldn't find one mite. All of his snakes not just the two I was going to purchase are acting and looking one hundred percent better. Many of them went into shed right after the mites were eliminated, including the female mojave. The better news was that I got the mojave to feed while I was there. I did this by asking my local shop for some soiled gerbil bedding. She didn't hesitate to take it.
I haven't officially bought them from him but I'm starting to feel like I might as well lol. Especially now that I've seemed to correct the issues. Although the guy seemed like he wanted to back out of the price he had asked before. So the possibility exists that he'll back out, since he now sees no mites and a snake without a feeding problem. All of which I corrected.
Well, I hope he does not back out on you and you can add to your collection. Good luck! I hope everything goes your way.