This ComforPedic 4" Gel Memory Foam Mattress Topper in Queen Size, listed at $599, is now $149 at Groupon Goods. Plus, shipping is free, making this the best deal we could find anywhere. It features memory foam to cradle and support you while you sleep, combined with gel to keep you cooler than traditional memory foam. It comes in 5 sizes in total, priced from $99 to $169, all with free shipping. Note: most orders arrive within 2.5 weeks from order date. Sales tax is charged in some states.