2002 Audi A4 HID light went out

I recently had my front left headlight go out on my audi. Upon returning from a trip, I noticed moisture in the housing and after researching I heard that moisture in the housing can ruin the ballast. I swapped out the working headlight from my right side into my left housing and still didn't get anything. I'm certain that the bulb is fine and the ballast is shot. Is this part something I can find and install myself? I'm trying to avoid the dealer at all costs.