I'd always suggest a paradox/seek outside pack. But that's outside of your budget. One option is this:
http://www.llbean.com/llb/shop/6439...;attrValue_0=Olive&productId=1077114Used with a drybag(s) it could be used as a daypack or a backpack. It's pretty comfortable and can carry a load.
Even after I bought my Paradox pack I kept this LLBean frame