Local vendor
We got one made for our 376. We used a local vendor in the area. They did it for under $300. It was about 4 years ago, so I don't know what the materialis worth today. If foam is directly proportiona to the price of fuel, $1,000.00 may be a good price.One trick they did show me. If the foam is deformed but not dry rotted, it can be steamed and it will revert to its original shape.If you want to spend some more they can make a layered foam mattress emulating a grand name. They use different density foams in the layers with memory foam being one of the layers (I think the top layer).We live in the Phila PA area and they are in Essington, PA. I would think here is one near you.Good luck,Mike D