here is my crummy opinion....
I was never one for autographed stuff unless it was personalized for me. I can understand that there exists a market for this type of stuff but you seem to be more interested in the book (and the information inside it) than the market value of a signed copy. From your post, you don't seem to want to profit from the book therefore how important is the autograph to you? If you plan on just keeping a copy of the book for future reading I don't see the autograph being that important anyway.
Anyway, it seems like you already know the right thing to do with the book so this is probably a moot point anyway.
I was never one for autographed stuff unless it was personalized for me. I can understand that there exists a market for this type of stuff but you seem to be more interested in the book (and the information inside it) than the market value of a signed copy. From your post, you don't seem to want to profit from the book therefore how important is the autograph to you? If you plan on just keeping a copy of the book for future reading I don't see the autograph being that important anyway.
Anyway, it seems like you already know the right thing to do with the book so this is probably a moot point anyway.