You wouldnt pay what I did for mine. lol. Try ebay, you don't need an expensive kit, they really arent used that much Tom. You also need to bear in mind that although they will light instantly when you 'flash' your lights, it takes 5-10 secs before you get the full light from them. If your the sort of person that uses them for a couple of secs to see ahead when your vision is low they won't be very useful. If however, you use them on very dark roads at night while there is no traffic they'll be awesome! The brightness of them was like that of a lorry with a whole bank of full beam lights..
Basically you just need a unshielded H7 HID kit. Don't get the H7R shielded ones, full beam bulbs are not of the shielded type as the principal is to get as much light as possible on the road surface. They're usually sold as H7s for halogen lights (H7R's) or H7 bulbs for projector headlamps (the ones you need). You don't have projectors in the full beam, but you really don't need the deflector either. Oh and make sure they are the short length ones, the very long H7's will not fit the shallow Vectra headlamps.
I wouldnt get above 6k temperature either, as the whole point of HIDs is to light the road up better, and the higher the temperature the less light output there is, because the bluer/purpler the colour, the less overall light is emited. The whiter the light, the stronger the illumination.
You couple that with the oem xenon projectors, and what you end up with is a much smaller light output. As xenons go, Vectra ones really arent that brilliant. They aren't bad, but the HIDs do a much better job in the Saab purely because the projectors are huge allowing for much more light output.
Here is what I used:
http://www.hids4u.co.uk/h7-hids4u-sl...-1-pr-165.html
My Saab uses these in the projectors:
http://www.hids4u.co.uk/h7-ultimate-...p-1-pr-64.html
I've always used
www.hids4u.co.uk as the quality is excellent, the cambus safe ones work perfectly and arent cheaply done, and the warranties are excellent.