HID uses a high voltage system to make an arc, that is what makes the light, not the filament like a conventional bulb. So there is the set of transformers and high voltage cables and all that stuff, so I guess you get your money's worth of stuff.

I was looking into the conversion, but I read a bunch of info that makes it not sound like a good idea.

1. the HID lamp housing is very different, there are people who make HID bulbs that will fit in the H4 lamp housing, but they don't perform as well as they should.

2. as a result of the low quality HID retrofit kits they stopped them from being imported to the US.

Sylvania used to make a good HID kit that replaced the 6054 sealed beam, but it was primarily low-beam only, and to get HI-low was quite expensive.

I got some e-spec 6054 housings that take H4 bulbs and they are quite bright, the pattern is like nothing else on the road here, and they are totally illegal, but if you live out of the states that's less of a problem.