I have one - right (passenger) side.
Car - 1.8 sport, 6 months old
Mileage - 21000 kilometres
Appeared - no idea when and how. Was pointed to me about a week ago by the garage when the car went for service. Could not be too old, because the front glass was missing but there was no dirt or insects inside. Could be though that the garage removed the broken glass that very day before showing it to me. The mechanic who did the car had already left, i only got to speak to the person at the counter. So, i did not get to see the pattern of the cracks either.
Cost of replacement (estimated, i did not accept it yet) - 2400 DKK (ca. 220 pounds), of that 1100 for the light itself (we all like their labour prices don't we

)