It's all subject to the laws of supply & demand. Consider the following:
A replacement master cylinder for my 74 VW Super Beetle is about $20 the last time I checked. A replacement master cylinder for my 71 VW Fastback is about $210.
I chose to rebuild the MC instead. I can't find a seal kit ANYWHERE!!! Makes one wonder where the manufacturers of new MCs get their seals!
Needless to say, the Fastback is still sitting on jack stands.
One of the downsides with market driven prices, is the lack of knowledge on part of the buyer. All too often with VW components, being air cooled and all, buyers don't realize they are choosing an inferior product, because it's cheaper.
When they have problems, they dump the "stupid" car on another unsuspecting buyer, or the junk yard. If this cycles repeats too frequently, the superior, more costly part, disappears from the market entirely.
Fortunately, I have not experienced the same problems with Chevy parts. However, it must be noted, my truck's in rather good condition consider its age!
Regards,
Mike