There is a fellow in the Phillipines that is trying to start selling premade horn nocks as well as horn for asiatic composite bows and self made bow nocks, etc.
I got two pair of his premade horn nocks for $10 a pair. They are pretty good, but I think he has some fine tuning to do before they will be generally acceptable. I hope Jaro or someone will work with him to refine his design. His workmanship is good, but the string grooves aren't quite right in my opinion. Easy enough to redo oneself. If I were to order more, I would have him drill the taper and rough out the shape, but leave the rest for me to fine tune (no final shaping or string grooves).
He also has mother of pearl, ebony, and snakeskins.
His name is Peter Cua. Here is his email address:
kusangloob(at)yahoo(dot)com [replace "at" with @ and "dot" with .]
Ken