They appear to be hand-made. Manufacturing niche toys is very much a chicken and egg problem. At scale, these could be made for $1. But that implies volume sales which would likely result in a bunch of people complaining that the puzzles were "broken" and "some idiot left out all the edge pieces -- 0 stars!"
Fair point sorry I totally missed that. I still think it's too pricey but you're right that that is a more expensive material and definitely deserves to be reasonably more expensive.