Actually, I now use the Sony fe200-600mm, and paid 1900 for that lens new.
Although the 500PF arguably has better image quality, with better contrast and clarity, I would sooner say that these lenses are very different, than calling one superior to the other. The 500PF gave me very good images on the D500, the 200-600 gives me very good images on the A1, with that noticeable bit of extra reach.
Is the 500PF built twice as good as the 200-600G? I don't see it, the 200-600 is heavier, but not built less well as far as I can see.
Well, IMHO I think you can't compare lens prices like this, because there is always a company internal price politics aspect to it as well.
But yes, if I am not afraid about a platform change, I have a better choice nad this includes getting more lens for less money and depending on what you do with it, the cheaper alternative could well be the better one, being it weight/agility, IQ, reach, flexibility or whatever.
Not talking about price, but for me it was still is right that I have sent back the Nikon 200-500 and get the 500PF, because of handling, IQ, AF speed, the fact that I need the long end 80 to 90%, ... you name it, but for someone else it could have been the exact opposite.