HID kit in reflector headlights = forget it. Super glare-y, poor light distribution.
Most cost effective = HID retrofit. Also require the most effort. With the bulb, I wouldn't bother going over 5,000K as it's all wank/ricer after that. Stick with 4300K as you can actually see at night/when it rains. You will get the blue flicker because that is produced by the cut-off shield, plus the light will be whiter. I recommend 'F3' fast-start ballast as they are pretty good for the price ($200 for a kit off ebay, if you go H1 projectors).
If you want to just swap bulbs, try Narva Blue Power (or blue 90/whatever they're called now). Works well for what it is.
Throw relays and thicker wiring on there as well, it helps.
But seriously, OEM is obviously best (if you can get hold of them), then HID retrofit.