If you too prefer to not have your book collection marred with price stickers or just have a vendetta against labels in general then this is the Instructable for you. This is the method I prefer as it is can be quick and most of the time there isn't a whole lot of mess to clean up (no guarantees).
sandpaper - 120 grit (or other coarse grits)
"label lifter" or plastic scraper**
paper towel/toilet paper
latex gloves (optional but recommended)
*I would think any lighter fluid would work but I find Ronsonol Lighter Fuel works best and is the cheapest (the one in the yellow bottle with blue on it), but I have had satisfactory results with Zippo brand fuel too. I guess you could also use Goo Gone but I personally can't stand the smell and find it's messier as it doesn't evaporate as quickly as most lighter fluids (not really recommended).
SAFETY NOTE: Lighter fluid contains naptha which can be dangerous to your skin, lungs and other important parts of the body. I would recommend wearing latex gloves and work in a well ventilated area. For your reference, the MSDS for Ronsonol Lighter Fuel: http://www.cooperbooth.com/datasheets/160606.pdf
**I have a Goo Gone label lifter that works great but you could easily make a scraper out of a credit card by scraping a beveled edge (like that of a chisel) by running a utility knife along an edge at an angle a couple times.
Step 1: Test the resistance of the label
If it doesn't peel off easily move on to Step 2.
1. Be careful of removing labels from book covers with a glossy finish without using the lighter fluid method, they sometimes come off easily but take the glossy coating with it and leave a dull area where the label was. It's usually unnoticeable but if you're like me, once you notice it you'll see it every time you pick up the book, for the rest of your life.