Head over to WalMart right now, where the blue Ozark Trail Walhalla 26-Liter Backpack is on clearance for only $11.99 right now, down from $24.97!
This pack is hydration compatible and has multiple compartments for lots of gear and storage. The adjustable sternum straps add extra stability. You can pick this up for free at your local store or get free shipping on orders of $35 or more.