what should the cost be to replace the lower control arm bushings? on 2005 Chrysler PT Cruiser

The car has 47,000 miles on it. Is this normal? What causes them to go bad?

Asked by for the 2005 Chrysler PT Cruiser
I'd say it's either due to defective bushing parts or rough use. Usually replacement bushings last longer than the originals, I don't know why..