I am having the common light flickering of the headlights on my 2006 A4. I was told to replace the whole unit but that is very expensive.
I was wondering if anyone has any experience with the ebay HID lights like these:

eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

What the headlights in my cars say is "H7 or D1S" please give me some insight on the issue.

 

I can tell you that those lights are definitely "Halogen Projectors" in there which means you'll probably also want an HID kit in order to get any of the color flicker or nice cutoff line. With that side, adding an HID kit will kill the projectors optics, as well as your ability to see "better". My advice would be to just retrofit your stock headlights with FXR projectors from theretrofitsource.com.

I just bought a 2005.5 A4, one of the bulbs is flickering so I ordered a new set of bulbs from ther site I mentioned to just see if it fixes it, if not, I'll be doing the above projector upgrade. Make sure if you do you also get the ballasts and everything you need. I had that setup in my previous vehicle and they will blow the stock projectors OUT OF THE WATER!

 

that is a very common problem.

start by replacing the bulb, see if that fixes the flickering.