what kind of car? how many miles?
how old is it? It is probably the front suspension needing to be rebuilt. Bushings, ball joints, some of the links etc.
I suspect that some of these items are worn on my 1985 300D project car (219k miles) because of the noises I hear when going over bumps while turning. I have rebuild the suspension on the "to do" list over the next six months.
I would guess that the cost could run anywhere from $200 to $400 per corner based on how much work you plan on doing yourself.