It has always seemed to me that someone with some free time and a metal lathe could make reasonable-looking replacements from standard hardware. It's an allen-head bolt of the correct threading with a hole down the middle and one side ground off. The adjuster is a thumb nut plus an o-ring. They wouldn't be exact copies, of course, but certainly workable.

Back of the envelope guesstimate would make $20/pair profitable for a hobbiest, $10/pair for someone with a dedicated machinist and more sophisticated tooling.