And that happens a lot. Unless the signing is by an author who rarely does so, the signature is worth maybe four or five times that of an unsigned book. When people approach him with books signed by blockbuster authors such as Stephen King or Anne Rice, Jerry is not inspired.
Inscribed editions are another matter altogether.
The more personal the inscription, the more the book is generally valued. Inscriptions made to close friends and family, such as the author's mother or husband, for example, boost the book's value.