eBags has the Timbuk2 Hidden Messenger Bag (Blue, Green or Violet) for $20 with free shipping. Features 90% recycled pet fabric, is 100% machine washable, measures 12.4" by 6.49" by 4.92", and folds down into a small pouch (6.5"x7.5"x1") for easy portability.
It's called "hidden" because after you pay for it, you'll never will see it...