I went to Under Armour Cold Gear 3.0 several years ago and it is AMAZING! I kept seeing the NFL players wearing UA in cold weather and found base layer clothing that was developed just for cold weather sportsman. At first the sticker price shocked me but once I took the plunge I really didn't care what it cost. I also bought the UA Cold Gear socks and wear them with Rocky Buckstalker 1,000 gram insulated rubber boots. Even in the coldest of weather I only wear one pair and if it gets down in the 30s I just add Toastie Toes...works like a charm.
I would highly recommend you check out the UA Cold Gear 3.0 mock turtle top and bottoms and socks.