|Especially if it is all machined by hand instead of being made from a mold.
From what I read on the internet, that plastic is normally machined. And looking at those plates, there are so many different angles to machine to spec! It might be easier to just make a slider/grinder to attach to existing set-ups. Using conventional skateboard trucks and hangers.
However, I'd really like for a long lost (deceased) relative to leave me a lot of cash right now! I'd buy them in a heart beat if I had the cash.