I bought a £25 kit off eBay
H1 55w 6k.
They are brilliant. The best "mod" I've done by far.
They are in my '95 M3 so are in projectors but I stripped and cleaned the lamp units and then lined the headlamp up bodywork wise then realigned the light output and they are amazing.
You can see for miles, they light up everything and don't upset other road users.

I'd say do it straight away.
Slowly but surely I'm fitting them to all my cars.
The next kits will be 5k as I think 6k has a little too much blue, 4300k is too yellow for me. Anything above 6 or below 4 is just chav.

I would also buy spare bulbs with the kit as when one fails you can't just pop to halfrauds.
I paid about £4 for a spare pair.