I'm..... thrifty and I try to be economical. I've bought plenty of base layers at TJ Maxx, Marshalls, Ross, but have failed to find good pants. I broke down and purchased REI Headwind pants for $60 (on sale) and feel like it is a good investment. Zippers on the bottom, room for tights or leg warmer layer, long enough to cover my ankles. The front does a good job of keeping the wind out and is somewhat water repellent and the back of the legs breathe. I consider these money well spent. I also spent about $60 on a neon yellow cycling jacket, also worth the money.

I don't ride in extreme cold, but keeping warm in more extreme conditions is probably easier to do with good outer layers made of appropriate technical materials.

You can often find good sales at end of season. Buy winter clothes in April and summer clothes in October.