HID bulbs cost $50 bucks each. Even for the good OEM ones. Its by law that OEM HID's have to be 4300K I believe. 4300K is the best temp for highest light output (lumens) meaning you can see further down the road, than with higher K lights which are blueish and darker. 4300K = closest to white 6000K= blue 8000K= purple. I don't mind 8000k so much except when someone puts hid's inside a halogen headlamp. The glare they have is pretty annoying. OEM HID headlamps have to be used with a projector headlamp to prevent the glare.