I haven't bought any but I would try the car spares and accessories place on Anagnostou Gogoni. If you were coming out of Chania on the Souda Road there is a set of traffic lights shortly after the road becomes two way. There is a Silk petrol station right on the corner. Turn right there onto Anagnostou Gogoni and it is after about 400 m on the right hand side.
You could also try the agent for the make of car. With the VIN they should be able to get an exact colour match.