HID kits and prices

Hi all, i have been looking for a decent priced HID for a while, and have come across this one. 55w HID kitI want to convert a set of Hella 4000 driving lights to HID as i need the extra light and enjoy the type of light HID puts out.

I contemplated a HID headlight upgrade for a long time, but i was a little worried about the legalities and all. Even though everyone is doing it, i would prefer not to cause an accident or get a defect. However it seems that this mob have kits that are only HID when on high beam and halogen on low beam.

Does anyone know much about this, will it work on normal H4 headlights or would it only be for twin headlight type systems like the 80 series? It surely seems the way to go, but just wonder how it works if its just for normal H4 lights.

Also what is a good price to pay for a HID kit, preferably would like a slimline 55w kit and digital type too, as everything i have read while researching points to them being the best. I have tried a couple of 35w kits from China in my worklights and stuff, they only cost me $25 or something and they are still fine, and the amount more light is awesome. They seemed very cheap and nasty at first but must say they have performed well for over a year now. I am guessing they are built nowhere near as well as the ones listed above also?

I am guessing that there must be a few blokes who have done there lights on here, so thought there should be some good info. I dont wanna spend hundreds of dollars on a kit, as i dont think that they would cost much to make myself. A 35w Philips kit costs about $500 here, yet they are under $100Aus in Europe and USA. A mate has a Philips kit he paid $500 for and there was no difference in output or current draw to my cheap ones.

I might put in an order i think on the above.
Cheers for any info