Any idea of the value of these books?

[Jack_Tar]

I have no interest in selling them and am not trying to do so. I was just wondering if anyone here had any idea what the value of these books might be. I can't seem to find any of this vintage (late 60's to early 70's) for sale anywhere. I only showed pictures from the GM book because that is the main focus here, but I also have full Ford, Chrysler, and AMC books as well as a 5" thick Imports book (not shown).
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181017-1.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181025-1.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181030-1.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181131-1.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181339-1.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181430-1.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181612-1.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181743-1.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181803-1.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181842.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181901.jpg
http://i375.photobucket.com/albums/oo196/NavyFirefighter1973/IMG_20120928_181912.jpg

[nova7579]

I see them and pass them up at swap meets for $20 to $40 a piece.
Brian