I just spent a couple nights digging and shopping, trying to come up with some warm, light bags that wouldn't break the bank for my scouts (under $150). Warm is certainly possible. Light is possible. But it's almost impossible to find anything warm and under 2 lbs that is also affordable. Here is what I sent the scout parents:
After last week's not-so-awesome experience with the Ozark Trail duck down "32 degree" bag from Wal-Mart, which turned out to be a 45 degree bag, I've been keeping my eyes open for a good deal on a decent, sub-freezing, sub 3-lb down bag. Typically anything with 600+ fill power down will be over $200, and anything with 700-900 fill power down will be over, or well over, $300. Occasionally one can find a well-made down bag for under $200, but they are usually 550 fill power down and over 3 pounds.
Here are some recent deals on 550-600 fp down, under 3 pounds, and under $150:
1) There is the well-reviewed Kelty Cosmic 20 degree bag which can often be found at $139 to $159, but I found one of last year's models at the Sportsman's Guide for $99 (the page says 0 degree, but I'm sure that's a typo, because Kelty's Cosmic 0 degree is usually 3 lb 12 oz, but this one is 2lb 12 oz, which is exactly the specs of the 20 degree model).
2) ULA equipment is currently offering a 2.6 lb 20 degree down bag for $130 if you are also purchasing a backpack.
3) Backcountry.com has the Kelty Light Year 20 degree down bag for $149 (not really on sale)
4) Finally, CampMor.com has a nice 600 fill power Sierra Designs 15 degree down bag that is 2 lb 10 oz for $149 ($100 off list price, Item #: 37417). This is the one I purchased for my son.