Erdnase is the bible of card work. Some of the information is a bit dated (it was written 110 years ago) but its still solid. You can find cheaper copies, but im fond of the Bible edition as well as the Indestructible one.
What information do you think is a bit dated? I'm doing some Erdnase-related stuff at the moment and I'm interested in the perspectives of magicians on the material, so it would be great to get your view.
http://product.half.ebay.com/The-Expert-at-the-Card-Table-The-Classic-Treatise-on-Card-Manipulation-by-S-W-Erdnase-1995-Paperback/881923&tg=info
I know it's not the bible ed. but all I'm sayin' is $25 is a little much.