Unless you have a chronic and severe mite problem, I would stay away from the mite sprays. I would suggest to you that you try to agressively treat you're snake in a water and iodine povidine solution mixture (about 2-3 drops of iodine in you're bathroom sink). Try to treat the snake twice a day. After bathing the snake, pour mineral oil in a cotton ball and wipe down the snake. Use q-tips to swab the snake's pits.
Make sure that you also throughly clean the snake's enclosure. If you have any wood in the enclosure get rid of it. The wood attracts the mites. If you have a glass tank enclosure (10-20 gallon tank) wipe down the glass and ends in mineral oil as well. Do this and you should be able to get rid of you're problem. Dont waste you're money on mite sprays.
I had a severe mite problem myself, I tried the treatment I specified above and my mite problem was gone in 4 days. I had this problem about a year ago, and I have never had a problem since. Hope this helps.