I looked into this recently and I found that Jansport has a model called the Big Student which is about 2200 cubic inches and has three compartments. Its rugged and can be had for about $20-25 on Ebay. It lists for $50 or $60. I also have an Eagle A-III which is definitely overkill. Its about 2400 cubic inches, a million straps, plumbed for a water bladder and everything is double stitched. I think it might be military issue. It costs about $100 or less on Ebay. Look hard at the Jansport.