I'm currently having the same issue, the ballast / ignitor shat itself on the drivers side. thought the bulb was on it's way out so I purchased new bulbs, and the drivers side was still not working. Swapped the bulbs over and confirmed it was the ignitor or ballast.
Tried tracking down a spare ballast, but no wrecker wanted to sell them without the headlight, so I had a few options:
-buy a second hand drivers headlight assembly ($700 AUD!! was the best price)
-find ballast online via ebay
-aftermarket canbus HID kit from local supplier
first option is well out of my price range.
Second was an easy option although could not find any locally, and there was no warranty or anything on the item.
So I opted for option 3. (I actually bought a pair of black housing depo headlight w/ angel eyes and the HID kit all together, as my passenger side headlight was starting to flicker) Everything should be delivered tmrw and I should be finished with the install tmrw to. Will let you know how I go.