Wind protection is key, but it doesn't have to be expensive. Wool alone is wonderful, but when cold air blows right through it and you're not riding hard enough to generate enough body heat to counteract that, it doesn't do you much good.

Depending on how cold your legs get, wind pants may be the hardest thing to find inexpensively. Some gusseted denim jeans, a size or two too big, over wool or knit polypro tights, might be a way to go.

Do you plan to commute through the entire winter? What kind of weather conditions are your limit?