'02 X5 xenon light issue

[Aleko]

The passenger side headlight (xenon) started acting up on my '02 X5 about a month ago. First, it turned purple/pink instead of the usual blueish white. Then, a couple of weeks after that, it developed a 2-3 second delay before lighting up. It has also failed to light up at all a couple of times and I'd get the "check your low beam" message on the dashboard. Both times it "fixed" itself by turning the lights off and back on again. Looking at the diagram, I see that there are 4 things that could potentially be a problem - the light bulb, igniter, ballast or the control module. I doubt it's the light bulb issue, so it's probably one of the other 3. Based on the behavior I've seen, it almost seems like the igniter could be the issue, but I guess it could also be the ballast dying and not supplying enough voltage to the igniter/light bulb.

Has anyone had this problem before or seen similar symptoms? Since all of the components are fairly expensive and most likely non-returnable (at least at my local dealership they have a sign posted that all electrical components are non-refundable), I'd hate to waste the money on the wrong part. Thanks in advance.