The Razer Sphex Gaming Grade Desktop Skin gets stellar reviews and is only $9.99 right now. It features high tracking performance on the thinnest mousing surface ever and is able to adhere to nearly any surface. While not quite the cheapest its ever been, I've only seen it this price or better a handful of times. If you're in the market, buy now at a bargain. Hit Gizmodo's review for more deets.