TomTop offers the Swissgear 15.6" Laptop Charging Backpack for $39.99. Coupon code "SWBP10" cuts it to $29.99. With free shipping, that's $33 off and the lowest price we could find. It includes a USB charging cable and features waterproof fabric.

Note: This item ships from China and may three to four weeks to arrive. The countdown timer on the product page does not reflect an actual expiration time and resets daily.