An autographed book by George W. Bush has value of $500 to $1200 more than the price of the book. If there is a personal inscription, the value increases again. The most important elements are, first, that the signature is authentic and, second, that it from the time after he was elected President of the United States. Even if you were standing at the table when the former President signed the book, it is still a sound move to have the signature authenticated by a reputable agency, and get a certificate of authenticity. Collectibles of this nature increase in value over time, and having a certificate is an insurance policy to help maintain the value of the autographed book.