My Lag 2 has just been booked into have the wishbones replaced on both sides. They are doing both sides and fitting for £170 inc vat. (Thats from a local garage). They also quoted they could do just the balljoints. By removing the rivots as previously mentioned in this Thread. The balljoints alone were £13 each and the Wishbones were £44 each. The parts were all sourced from our local Motor Factors. So it is possible to do just the balljoints, but for the extra cost, least all parts on Wishbone are new.
Hope this helps somebody