Not wanting to jack your thread, but I've been wondering about these el'cheapo HID systems:
http://www.ebay.co.uk/itm/291019662888
That's two 'bikesworth' of lighting for £23 I've heard varying reports about them, I figure if one bulb/ballast lasts a year then i'd be happy. And doesn't require any actual "wiring" just plug and play.
Anyone actually tried them?