Dell Home offers the Timbuk2 XPS 18" Laptop Messenger Bag in Black for $79.99. Coupon code "PTKBD?9L1C$11W" cuts it to $71.99. With free shipping, that's $20 off list and the lowest total price we could find. This convertible bag can be carried as a messenger bag or worn as a backpack. It accommodates laptops up to 18" and features a waterproof exterior an zippered closures.