Tanga offers the Ducti 15" Laptop Messenger Bag in Black or Blue for $17.99. Coupon code "DEALNEWS" cuts it to $16.99. With free shipping, that's the best deal we could find for such a laptop bag by $40. They hold laptops up to 15.4" and feature interior and exterior pockets.

It's also available for 12" laptops for $16.99 after the above coupon.