Dale, I don't think you can find a decent 1 lb synthetic bag unless its just for summer use.
I recommend the Montbell #7, in alpine (zipperless) for $150 (2006 model, 1 lb, 725 fill power, direct from an outlet in Japan), or 2007 zippered #7, 1 lb+ in 800 fill power.
These bags stretch as you move and sprawl out; no other bag can use this world-wide patent on full length stretch baffles. The interior baffles eliminate much of the dead air space, and continuously maximize loft by seperating the inner layer away from the outer layer. My #7 has more than 2" double thickness loft.
I used my 1 lb bag comfortably cool at about 30'F last winter. Think about that; a 1 lb winter bag.
PM me if you want the 2006.