Because of the recent discussions on retrofitting HIDs into Halogen housings... it occurred to me the other day that there is a low cost alternative: Catz ZETA systems. It uses ballasts and some sort of cycling technology to make halogen H4 bulbs burn slightly brighter... and being a bulb with a filament, it's perfectly legal according to DOT and NHTSA.
Granted, it's not a real HID system, but it will give you slightly more light output... possibly at the expensive of shorter bulb life. However, a halogen bulb is significantly cheaper than a HID bulb (less than 10% of the cost of one HID capsule). The other advantage is that you maintain the same high and low beam filament location so your lighting pattern will not be compromised or affected. With HIDs it's alway a gamble on whether the capsule will be at the right location or not. If the capsule is in the wrong place, you could massive glare.
I have a contact at FET-USA who might be able to offer group pricing on the Zeta kits. Let me know if you're interested. If there is enough interest, I'll take a closer look.