On my low milage (45K) Ranger, the four rubber ball joint covers are completely rotted apart. Mechanic says that's not unusual and in another 40-50K miles I'll probably start getting noticeable wear and want to replace them. He didn't mention a cost and I forgot to ask. I see 4 new joints advertised for anywhere from $30 to $80 per set. What is a reasonable guess at installation cost? Or should I just let the existing ones wear on for awhile and not worry about them?