I really really liked one called either the penny pincher's guide to WDW, or the cheapskate's guide to WDW.
It did help to save me $$ years ago.
One tip I learned is to freeze juice boxes and/or water and take those (and snack type things like oranges and cracker packs) with you in your backpack. Also, a stroller comes in handy, even if you don't have a child, it's a great place to have the backpack, towels, and other accoutrements.
I recently bought Disney on a Dime, by Chris and Kristal Carlson, and can't really recommend it.
If you're curious about certain books, you can go to
Amazon's website and check the reviews, or, just get them from your local library (although they may not be up-to-date.)