Yeah, before I bought the Disc Eraser, I used sandpaper on my old CD-Rs. It's messy, alot of dust gets everywhere and it's not something you want to do in your office or indoors. I also tried hammering and cutting them up, etc...basically all the methods that people recommend or have tried. I even bought the CD shredders and destroyers. In summary, the Disc Eraser IS the best way, hands down! And it isn't expensive.
It's definitely the quickest and safest way to disable a CD, creating NO WASTE material. I think it's a product of the future, because it promotes recycling, and the environmental concerns are increasing with the number of unwanted CDs and DVDs.