Seriously. The rear 80% of an MP40 tube with the rear sight base removed is worth anywhere close to that? What’s the trunion piece worth? Or is it that it could be a single saw cut with the front end trunion piece tossed in later or sold separately?
If you want to build a semi out of an original receiver, this is as good as you’re going to get. I wouldn’t pay that much, but I won’t judge those that did. It’s a rare find.
I know an old collector with a chunk like that, maybe more, old saw cut, with the rear sight and I believe matching. It's for sale. I have no interest because I'm not building a semi.