Wenger SwissGear GA-7391-13F00 Valve Backpack (Black/Red) for $29.99 shipped.  Here is a screenshot for your reference.  This backpack fits most laptops with up to a 16" display and features Apple iPad or tablet padded pocket, Checkpoint-friendly compartment, essentials organizer and more.  Most places have this SwissGear backpack for about $60.