At the age and mileage of your 190E, and presuming it's not been done before, I think you got your money's worth out of the rubber parts on the car! First, you'll need to find out if they're just changing the ball joints from the lower control arms by pressing the old joints out/in, or are they going to be replacing the control arms with a new ones that have the ball joints pre-installed?

If not done already, it might not be a bad idea to have the tie rod links replaced, steering shock replaced and have the control arm and roll bar bushings replaced and the drag link.