You can make your own, a hot knife is not all that expensive, just cut a piece to fit the bottom, and then a 2nd piece with cutouts for your gear. Foam is readily available by the sheet in various densities. There is a foam store in Spokane that will even cut foam for you, but I just have bought it by the sheet and cut it myself for other purposes.
Foam can be made to order by mixing two chemicals together in different proportions to get the right density, and pouring it into a mold. I had a company make custom mold to use for a electrical spacer to hold power feeders into the correct arrangement so that maintenance people would not accidentally cross the phases for a critical application. We had to experiment a bit to get the correct density, so that it would not tear.