Bang for your buck try looking on montbells website http://www.montbell.us/ for a bag several great choices for around $200 and very light I have a SS. Down Hugger 650 30deg and use it even below freezing temps, just add a down sweater and a silk bag liner. In the summer I use the liner alone

Good Luck
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"In the beginers mind there are many possibilities, but in the expert's there are few."
Shunryu Suzuki