Not all lock cylinders are equal, some are better than others at taking the load. Had a chevy with the same problem as BillLiptak's ford. Local locksmith said that he would be happy to fix it for $$$, but repair would only last a year or so before the plastic part that was bad would wear out and need to be replaced again. So either get used to spending the money, or learn to live with it.

Also not all key users are the same either. Have seen many keys and cylinders worn out by heavy handed key users. Some people stuff the key into the cylinder like they are driving a nail not gently pushing a key into the ignition cylinder.