How expensive is it to fix a broken headlight?

I've been wondering about headlight repair costs since I accidentally cracked mine the other day. It's one of those things you don't think about until it happens, and now I'm curious about what I'm looking at financially. I know it can vary depending on the car and whether it's just the bulb or the whole assembly, but I'd love to get a general idea of what people typically pay to fix a broken headlight.