Since you are in PA, you can drive to Campmor in NJ, or do what we do and just buy online from them. They are the best for low price, good gear. Look at the brands Kelty and Campmor's own brand. North Face, Big Agnes, and Marmot are also good brands. 3 lbs is the target to get under. If I was buying for a 12 year old, (actually I am this year, for my daughter) I would buy a bag that was close to the largest adult in the family. Unless you want to replace it in 2 years, he will outgrow it if you don't.