Sears offers the Serta Perfect Sleeper Harlington Plush Eurotop Mattress in King or California King for $779.99. Coupon code "SEARS35OFF300" cuts that to $744.99. With free shipping, that's $1,205 off and the best price we could find.

Note: The coupon also applies to the other sizes, dropping the prices as low as $364.99; the Queen size model costs $434.99 after coupon.