I am sure you can with a little skill change the led's also. Need a dead one to test if anyone wants to test this theory
If it's anything like the high level rear brake light then not as easy as you think. The casing is hermetically sealed and I couldn't take it apart without causing irreperable damage to the unit. I gave up in the end.
If I remember rightly, I think they are about £20 ea for the mirror leds.