Some museum must be missing this
You’d think he’d be at least not stupid enough to not remove the sticker. Is it valuable?
He has all kinds of “crap” for sale. 😎
In the current market, that's maybe a tad high for a legitimate seller, but not extreme. I have seen them go for twice that in prior years. Price depends on the maker, somewhat on the year made, any special characteristics it has, and perhaps on provenance if it was used by a famous surveyor or for a particularly important boundary.
But there are serious collectors and historians of the technology who, if they examined it, might be able to identify it and its history of ownership. I would be astonished if anyone walked into a second hand store to sell such an instrument because they found it in the attic, and the sticker is almost conclusive that it was stolen.