Just bought a Mountain Hardware Phantom 45 bag on clearance at REI. It appears to be a high quality bag. According to Mountain Hardware it weighs 1 pound 1 oz. It is even cheaper on the internet if you google around. To prevent over-stuffing, I bought a larger stuff sack than the one that came with it, which seemed a little small. Near as I can tell it is NOT a sew through design as someone else mentioned. You could go way lower than its rating with a puffy jacket and other supplemental clothing, which you should be carrying anyway. My other bag is a REI Sub Kilo rated at 20 degrees which is too warm in the summer for the Northern California Sierra.
