Roger, from what I see the prices must be figure by a formula more complex than just surface area. They must be putting a value on each format based on volume, cost of production including confectioning etc.. I
I would not be surprised if to make some sizes, they actually start with a larger size, and then have to cut it down by hand, throwing away the trimmings. Also they may have to make the box by hand, and or cut a filler piece for a larger box so that it is packed securely.
If they had to make a tool to cut the film, your cost includes part of the cost of that tool.
Charles MacDonald firstname.lastname@example.org
I still live just beyond the fringe in Stittsville