Sam's Club offers its members the HoMedics Thera P+ Deluxe Quilt Top 14" Gel Memory Foam Queen Mattress for $399 with free shipping. (Non-members pay a $39.90 surcharge.) That's $233 off list and the lowest total price we could find. It's designed for stomach and side sleepers and features a removable mattress cover. Deal ends December 2.