These aren't buckling spring, or even "Prototopre" as far as I know, but they do look nice from the photo:
https://www.ebay.com/itm/124283612937This appears to be the same thing with no photo:
https://www.ebay.com/itm/114335252414I'd buy one to try it were they not so expensive. I wonder how they compare to the "Quiet Touch" rubber dome Model Ms built by IBM. (I know the Unicomp Quiet Touch boards are not well reputed.)