I have used a backpack from Uphill Down (http://www.uphill.com/
) for my notebook computers for several years, and have really enjoyed it. They have several available in your price range that don't scream "Computer" for all the world to see. Some advice - WIDE PADDED STRAPS! A computer is amazingly heavy when you have to lug it around over any distance. Also, the more padding around the computer the better it has saved my bacon dozens of times.