if the damaged alloys are on the same side, the colour wont make a difference if its marginally off. if its on opposite sides, then get them all done, because that colour is a B**ch to match locally. there is a place in Brum, but its too far for you (called Speedwells), the guy works on top end cars etc, and his prices are between £150-250 for a full set.. and they give you wheels to use till yours are done.