I've gotten into the habit of shopping Sierra Trading Post online, putting things in the cart, and leaving them there, then checking each time I get a coupon in my email. The price fluctuates and eventually I get a really great combo of coupons. Like the $544 in gear (sleeping bag, snow goggles, winter boots) I got for $200. The bag is a good one, too, a Marmot EN rated winter bag.

They have a great selection of mid to heavy weight base layers, and frequently other things of use to the backpacker such as rain gear, wind shirts, fleece... I've gotten great deals on Smartwool socks and gloves.

Costco also has wool socks, and I saw Danner boots there the other day. Also they have a fleece balaclava - if you are easily chilled the balaclava can be nice and warm for sleeping in with your mouth/nose covered.