Jon's are $108 a pair.
Bob's are $450 a pair.
That must be some really expensive powder coat.
And a Schoeps KCY is around $900 - so what's your point
The KC5 couplers, a more valid comparison, are $634 a pair, last I looked. I could tell you why the KC5 is a better product, but I'll wait a while.
CNC machine time is priced as a commodity in dollars per hour. There are many thousands of shops that can make these parts. For cheap.