Amazon has the Teton Sports Scout 3400 Internal Frame Backpack for $53 with free shipping.
Product Features:
* Compact internal frame backpack with a capacity of 3,400 cubic inches or 55 liters
* Dual aluminum stays with contoured shoulder, lumbar, and waist pads
* Height-adjustable shoulder straps accommodate wide range of torso lengths
* Top-loading main compartment, sleeping bag compartment, and pair of side zippered pockets
* Attached rain fly; compatible with most hydration systems; weighs 4.5 pounds empty
Amazon.com: Teton Sports Scout 3400 Internal Frame Backpack: Sports & Outdoors
Teton Sports Scout 3400 Internal Frame Backpack $53 + FS 
