Ditto, the wicking fabric for next to the skin. I've tried to get by with cotton t-shirts and long sleeved jerseys, but they do get clammy.

I liked merino wool jerseys but they're very expensive now. Polypropylene long underwear tops and bottoms are affordable and readily available at most local ski and winter sports shops. Silk is occasionally available surprisingly affordably at discount clothing stores, especially toward spring and early summer.

For windbreakers and rain-resistant jackets, Nashbar, REI and a couple other discounters have some very good sales right now. I didn't have a rain jacket and just bought a Shimano Storm Jacket from Nashbar for about 1/3 of the original price. Very comfortable on a breezy high 30s/low 40s ride this weekend.