We have briefly discussed this book once before
http://rogerjnorton.com/LincolnDiscussio...d-354.html
It's hard to pass up a book on a subject you are intereseted in at that price, even though it may not be very good historically. Sounds like you got a good deal, just let us know after you read it if you think you paid to much.
I've bought several books off Amazon where the shipping costs were more than the price of the book. I usually don't regert buying them, although I know going in it may be a poor book. But it's a fun feeling when you get a winner. (the one I just posted on yesterday written by Ed Steers was a winner)