This Serta Deluxe 12-inch Queen-size Memory Foam Mattress drops from $899.99 to $464.99 at Overstock. Plus, shipping is free! This was the lowest price we could find by $160. 106 Overstock customers rated this item an average of 4.4/5 stars. It features a 3-layer design with a 2.5-inch premium memory foam top layer. It also comes in other sizes at varying sale prices. There is no sales tax (except UT, KY, PA and NC).