Problem under front of car

When I drive my car there is a big cluncking sound on the front of my car. What could it be? How much to fix?

It could be a lot of different things and there is no way to say what or how much it would be without actually looking and diagnosing. If you wanted to try to describe the exact conditions under which the clunking occurs then people could make some guesses. But they would still be guesses. You’re just going to have to take it to a mechanic. Find a local mechanic, with a good reputation who is not at a corporate chain type of place.