Gel Memory Foam Queen Mattress in Warren, MI

We have a Sleep Innovations Novaform Gel memory foam mattress, Model # M-14G3LAYQ, Queen size. It was purchased brand new, removed from the box, and laid on for less than two minutes. It has never been slept on. Our home has no pets, and is a non smoking home. This mattress has a 20 year warranty, and is being sold at Costco for $600.00 and on Amazon for $700. We are asking $450.00 O.B.O. . All paperwork and warranty cards ARE INCLUDED, as well as original packaging.