Mitsuke makes many, many different types of pins and are popular here in Japan. They are all pretty expensive though.
The triples are going to cost more because of the process... Dipping multiple times in different metals.
But yeah... that is crazy money. In my opinion, your run of the mill stainless steel pin will probably get the fullest spectrum of overtones of most metals, in my experience. Titanium is good too...
Any heavier metals get you a darker, warmer, wetter but sluggish sound. - tungsten is very heavy.
Carbon has a quicker articulation than any metals, but with a more brittle tone - less core to the sound.
Mitsuke makes 10mm rods that fit in standard endpins. I've seen Carbon, Titanium, Tungsten, Brass, Brass over titanium Core hybrid (very popular), Brass over tungsten core hybrid , Brass over copper over titanium triple.... And others...
I even saw brass over a carbon core once... But I don't think it is usually available...
