Campus111 via eBay offers the Eaglewill 20-Liter Hydration-Compatible Backpack in Black or Green for $9.99 with free shipping. That's tied with our mention from two weeks ago and the lowest price we've seen. (It's the best deal now by $2.) This water-resistant backpack accommodates hydration bladders up to two liters (sold separately) and features a large main compartment, two front pockets, bottom mesh bag, and adjustable padded shoulder and chest straps.