Hayneedle offers the Signature Sleep Memoir 8" King Memory Foam Mattress, model no. 005474396, for $156.55. (Make sure you choose King in the size drop-down menu to see this price.) Apply coupon code "DE-2437" to cut that to $140.89. With free shipping and excluding the below mention, that's the lowest total price we could find by $16, although most retailers charge $240 or more. This hypoallergenic mattress features 2" of high-performance visco-elastic memory foam, 6" inches of high-density poly base foam, and a knit fabric cover. Deal ends October 30.
A close price: Amazon has it for $143.04 with free shipping.