I'm lurking on Amazon for ideally 1/2" & 1/4" but this seems rather expensive on a $/volume basis. I want to make some foam cut outs from sheet stock for instrumentation type protection. Would this be better sourced at a local plastic supply store, or is the material just plain expensive? I usually keep scraps from shipping boxes if its the right stuff (not really sponge foam , its more of a denser material, I suspect polyurethane flexible foam?)