Hulislem via Amazon offers the Cylen Home Ventilated Memory Foam Orthopedic Seat Cushion in Blue for $22.92. Coupon code "6OZB8UMM" drops it to $13.75. With free shipping, that's tied with our mention from a week ago as the lowest price we've seen. (It's the best deal now by $18.) It features memory foam with an activated charcoal-infused bamboo core, an anti-slip bottom, and removable washable cover.