Today only at Amazon, LUCID by LinenSpa 12" Plush Triple-Layer Memory Foam Mattresses in all sizes are at their lowest prices ever. Here's the breakdown on these 25-year warranted mattresses: Twin: $199.99, Twin-XL: $239.99, Full: $271.99, Queen: 311.99, King: $423.99, Cal-King: $429.99. I have been sleeping on a 10-inch version of this mattress for about six months now. It was a bit of a transition coming from a spring mattress, but after the first few nights, I knew I'd never go back.