I have the factory HID headlights on my '05 but when I bought the car it came with a rather large scratch across the front plastic of the passenger side headlight.

The question is this: Can I just buy the outer casing, say from someone with a used one, or do I need to purchase the entire assembly to replace this ugly thing? In otherwords, how does the headlight assembly fit together?

If so, is anyone selling? I will put a WTB request in the marketplace as well, but while we're on the subject...