My Bag Factory Store via Amazon offers the Tocode Water-Resistant 15.6" Laptop Backpack in Black for $39.99. Coupon code "IS7AKWHA" drops it to $19.99. With free shipping, that's $20 off and the lowest price we could find. Deal ends July 31. Features include:
  • external USB charging port
  • padded sleeve for laptops up to 15.6"
  • anti-theft pocket
  • padded mesh back panel
  • adjustable padded shoulder straps
  • leather grab handle
Note: It doesn't include a portable battery pack.