Quiksilver via eBay offers its Quiksilver 1969 Special 28-Liter 15" Laptop Backpack in Quik Red Stripes or True Black for $25. Apply coupon code "PSHOPEARLY" and check out with PayPal to cut that to $20. With free shipping, that's the lowest price we could find by $15, excluding the below mention. It features a 15" laptop sleeve, two large main compartments, multiple zip pockets, and padded ergonomic shoulder straps. Deal ends November 20.

Note: The above coupon can be used twice per PayPal account.

A close price: Amazon has it in Moroccan Slash for $22.13 with free shipping for Prime members.