The only place other than main dealer would be a breakers if your lucky to have a new car wrote off.
This i think would be dealers only for a couple of years yet IMO
Have a look on lings as a guild there not cheap
And the other thing to remember is that the ones on the Type S, or ADAS equipped models is that they are HID/Xenon units and I guess will cost a lot more than £200 per corner!