Amazon has the Oscaurt Travel Anti-theft Laptop Backpack for $37 - $7 off with coupon Q5BJ9EPG = $30 with free shipping. Features anti-theft design, USB charge port, water repellent fabric, reflective tape, several pockets, and adjustable shoulder straps.
Ends 7/24. Proozy has the Champion Capital Backpack (4 colors) for $15.99 - $6 off with coupon PZY999 = $9.99 with free shipping. Features padded adjustable ventilated shoulder straps, top carry handle, padded laptop sleeve, fits most 15" laptops.