agreed, that stuff is expensive as hell.
I had the option of going sony for my longest lens, but after seeing sticker shot, I opted for a less expensive alternative. Sure, the sony would work with all of my lenses, but I was going to use it for an adapted lens, and the third party alternative cost me a whopping $40, with no noticeable degradation to IQ (1.4x teleconverter)
I would like to do BIF with my a7riii, but the only option for that now is the Sony 100-400 + the Sony 1.4x extender, right? Sticker shock!