Sears offers the Serta Amber Creek King Gel Memory Foam Mattress, model no. 500570587-1060, bundled with two Serta Sertapedic Twin XL Box Springs, model no. 500552699-5020, for $609.99. Coupon code "SEARS5OFF50" cuts it to $604.99. With free shipping, that's $1,015 off list and the lowest total price we could find. It features 1" CoolTwist memory foam, a foam core, and ComfortLast construction to resist sagging.
Of note, Shop Your Way Rewards members will earn a Sears credit with this purchase and may be eligible for additional credits and discounts.