Hmm I bought these and had no problems at all:

UltraBlock Zippered Mattress Protector (Queen) - Waterproof Cover Stops Dust Mite, Bed Bug, Spills, Bedwetting - Hypoallergenic Encasement with Zipper - White a.co/d/594j8Rh

Dust Mite and Allergen Proof Pillow Encasing (Cover); Premium Microfiber (Standard Size) a.co/d/8NZkbyT

Pricing for both combined being less than $50