Most of the listings on ebay are for 1 set of lights (Hi/Lo [H4], High Beam [H7] or Fog [H11]) + the ballasts and everything you'll need to install. I'm also looking at ordering some very soon, from what I've seen they are generally 80-100 $ for each set of lights (H4,H7,H11). As many here have said, I'll probably just go with the 6000k 35w slim ballast Hi/Lo (h4) for now, maybe get the fog lights later on, as the high beam isn't as necessary and better off getting the Phillips diamond vision if anything. They mostly come with either 55w and 35w ballasts. IMO the 35w is the way to go, mainly because it is still very bright, but I still want to be cautious of annoying every other motorist. The 35w is also a smaller ballast (easier to fit) and more energy efficient. For extra effect I recommend getting some of the LED H10 parker lights which you can use for the interior, number plates, parker lights etc etc. You should find some good links for them in the HID thread. Hope this has helped, anyone feel free to correct me on anything as I don't physically own HID light's yet and am only going on what I've researched.