Amazon has the 19.5" Ful Refugee Laptop Backpack (ABFL5149-001, Black) for $39 with free shipping. Features made from 1680 Denier ballistic nylon, lightweight, durable and offers resistance to punctures, tears, and abrasions, holds a 15" Laptop, has MP3 pocket with headphone audio port.
Has good Amazon Reviews.
Amazon has the High Sierra Pathway 90L Internal Frame Hiking Pack (Pine/Slate/Chartreuse) for $61 with free shipping. Retail price: $123. Has excellent Amazon Reviews.