*Projectors
You can use cheap ebay-type H4 housings and then toss a set of bolt-in projectors (MADE for HID) for less than 400 total with wiring, bulbs, ballasts, projectors, ect. And that's for a bi-xenon (Hi and low in one projector) setup.
Go onto
www.retrofitsource.com and look at their easy retrofit kits.
Also jump onto HIDplanet.com and do some research and get more familiarized with HID in general.
I throw empty glass bottles at assholes who just toss a cheap HID kit into their halogen housings and throw light glare everywhere. That doesn't help you, OR oncoming traffic see any better at all. HID is only truly worth the cost and effort if you do it properly, so if you are only wanting it to look cool with purple or blue headlights, don't waste your time and money. If you don't want to do a retrofit for HID, you can look into upgrading to an after market headlamp harness, a set of quality Hella crystal halogen housings, and pair of silverstar bulbs. That will give you vision comparable to OEM level HID setups.
That's my .02, good luck!