I mostly stay out of pet stores, since I consider them germ factories. My dogs don't need that, my snakes don't need that, ditto rats and birds. I buy equipment and supplies like substrate on-line. That way it hasn't been sitting for weeks on the shelf underneath some pet store snake bin with a bunch of stressed hatchlings. Don't know how well a mite can grip onto the plastic packaging.
Never had a mite infestation, and I hope I never get one!