Walmart offers the Living and More 8" King Memory Foam Mattress in White/Gray for $99 with free shipping. That's $137 off list and the lowest price we could find. Buy Now Tips Mattresses on average take 48 to 72 hours to decompress and sometimes in special cases up to a week to return to its original, plush shape. Features measures 80" x 76" x 8" Model: 569022271