eBags via eBay offers the SwissGear Travel Gear 18.5" Scansmart Laptop Backpack
in Black or Gray, model no. 5903, for $49.99
with free shipping
. That's $90 off list and the lowest total price we could find. It features a padded laptop compartment, zippered mesh pocket, organizer pocket, shoulder strap, airflow back system, and water bottle pockets.