Hulislem via Amazon offers the Cylen Home Ventilated Memory Foam Orthopedic Seat Cushion in Blue for $21.99. Coupon code "6CPWVGSG" drops it to $13.75. Plus, Prime members bag free shipping. That's tied with last week's mention as the lowest price we've seen. (It's the best deal now by $12.) It features memory foam with an activated charcoal-infused bamboo core, an anti-slip bottom, and removable washable cover. Deal ends January 31.