ccf is available at a reasonable price and by-the-yard at many upholstery shops. I've found very high quality foam on the A1 Foam and Fabrics Website
. It is on a 60" roll, so be aware that you'll need 2 yards to get a 6' long piece.
The mini-cell foam
here is about the same weight but seems like it might be slightly more warmth efficient, but at a bit higher price. I found the 1/16” mini-cell skins to be more like 1/8” thickness