+1 on thrift stores. I get all my running /cycling gear (except pocketed jerseys) there. You want combinations of:

Top
1. Long sleeved wicking or sports/performance material shirt
2. Short sleeved jersey on top of that makes for added core warmth
3. Old, thin (easy to pack) wool sweater on top of that
4. Wind-resistant jacket on top of that
5. Make your own balacava - buy a stretchy, tightly woven fabric turtleneck at goodwill (black is good), cut it out "dickie" style and you've got yourself something for under the helmet that also protects the neck.

bottom
1. Bike shorts
2. Long smartwool (make the investment) or alpaca socks over a pair of peds, or long acrylic socks with sandwich bags over the toes, inside the bike shoes.
3. Yoga capris (for non rainy days), athletic "gym" pants (wind/rain resistant) for rainy days, and ski pants for snowy/icy days. All can be found at Goodwill. Pants can be cinched with velcro from heads of romaine lettuce, or rubber band.

Hands: I use my regular cycling gloves under a pair of polarfleece mittens. But my hands get hot easily.

Don't overdress. It's worse than being a little cold.