A best bet is the High Sierra Swerve 15" Notebook Backpack in Black (pictured) for $39.99 before the above coupon, $31.99 after. With free shipping that's the lowest total price we could find by $8. This backpack accommodates notebooks up to 15" and features multiple interior pockets, mesh water bottle side pockets, and more.
Of note, eBags has an ongoing 25% off promotion (sans free shipping) which may yield a better discount on select purchases, however, numerous exclusions apply. (This discount shows automatically before adding the above coupon.)