http://www.hid-online.com/products/-Philips-H1--HID-conversion-kit-4200K.html
Here's a Philips one. There are other brands for less than 100 quid. 'Hids4u' is another site for them.
The 4200k is the OEM colour temp of most cars, 6000k is slightly blue in colour like some range rovers but not chav and still very effective.
It's easy to do but you'll have to drill a hole in your headlamp rear cap to fit all the cables through. The caps do have a contraption to fit some wires through but not all four needed in this conversion.
It's one of the first things I did to my car and it passed mot no problems with a straight clear beam pattern.
I used a 35w conversion but there are 55w conversions should you want the power of the sun at your fingertips.