How much should it cost?

Hi my car just failed its MOT and needs a new Power steering box and 2 new sills. Does anyone in the uk know of what sort of price i can expect to pay for either the parts or the fitting? I dont want to get ripped of and if its too much i may have to get rid of the Vitara :(

BTW my Vitara is a 92, 5 door, 16v JLX SE. Many thanks :)