I've bought numerous books for my golf/GCA library -- well, let's just say economically -- that had nice inscriptions inside. I am always prowling antique malls or even garage sales for such things. In most cases I am under the impression that the recipient became deceased before letting go of the book, and then the volume got swept up in an estate sale because the children and/or executor didn't pay any attention.
BTW, my (thrifty) wife would KILL me if she got wind that I spent $2600 on a single book. Though … if it was a lot of, say, 15 volumes, each with some significant, defensible interest, I think I could talk her into putting the weapons away!