Hi: I am new to this site and somewhat new to firearms. I am wondering about a friend of mine's .45; he just bought it and now he wants to sell it. Does he know something I don't? Is it a good gun? How much is it worth? He said he paid $650 for it brand new. Also why do gun value books differ so much from book to book? I looked at 3 and they all seemed to vary in price quotes.