I knew one of the legendary dice makers. He was an engineer and master craftsman. He had tens (if not hundreds) of thousands of dollars of equipment and an encyclopedic knowledge of raw materials, their properties and where to find them. He made all sorts of dice.
Great dice take a lot of skill and investment.
As to buying them, you will want to find someone who has a personal relationship with a dice maker and you will have to know exactly what you are looking for.
Quality work like this will not be advertised on the internet and even once you have a lead, they may or may not sell to you simply because.
If you want some dice with which to amuse yourself, most well stocked magic shops will have some that will prove fun.
If you want professional grade, expect to pay several hundred dollars and spend some time earning the trust of those who have what you want.