Ending today, Kohl's discounts The Big One Gel Memory Foam Mattress Topper for $29.99. Coupon code "FORYOU20" cuts the price to $23.99. Choose in-store pickup to dodge the $8.95 shipping fee. That's at least $3 under our mention from a month ago, at least $76 off list, and the lowest total price we could find. It's available in twin, full, queen, and king sizes.