I agree, I am not sure I would risk exposing mites to my entire collection for a "good price."
If you are positive that this snake is something you really want, I would recommend finding/creating a space in which you can completely isolate the sick snake from the rest of your collection.
This will help reduce the risk of exposure until you can make sure the mites are completely gone (while taking the necessary steps with products like PAM and/or other meds).