I second the recommendation for smartwool snowboarding socks. They are incredibly comfortable, and the extra layer of padding on the shin which is meant to prrotect against boot chafing has the added advantage of extra wind blocking while bike riding. None of my winter gear is specifically for biking (except my helmet), and for me the essentials are: warm mittens (my fingers get too cold when they are separated by glove fingers) , wool socks, synthetic fuzzy pants from REI (that wierd fuzzy stuff spun from pop bottles, can't remember what it's called), a regular winter coat, and some sort of hat/scarf combo or balaclava. I also adore my ski goggles, but if you are on a budget start with good gloves or mittens and quality socks and layer the rest, buying quality pieces as you can afford.