go to an art supply store and get some Bestine. it takes price tags of off paper with ease. I used it to get all the price tags off my action figures.
you have to be very careful with it if you try to use it to get price tags off of cartridge labels though. it will take the price tag and the label itself off if you use too much. it also eats the color on N64 labels.
it's actually a rubber cement/spray mount solvent.
That is some good to know information.