WOW I wasn't logged in when typing my reply OMG that sucks time to retype it.
I'd like this to help update this thread with out starting a new one in hopes that since 2011 others have attained more knowledge to contribute to this thread once again.
So I ran across this while searching for light fixtures for my 34g solona that I'd like to use for a reef setup until I found that the seams are dry rotted but that's another topic. I'm also interested in the capabilities for freshwater planted tanks as I will be now focusing on setting up my 30g freshwater.
Seeing this reminded me that my buddy used to order HID kits for cars really really cheap like others have stated already. The low cost of the bulbs and ballast is really attractive and got me searching which is how I ran across this thread.
Please note that automotive HID headlamps and fog lights are MH bulbs and are called xenon because of the xenon gas that is present and used as part of the ignition process instead of argon.
Although another thing to consider marine metal Halides and automotive HID bulb compositions maybe different and probably undergo stricter quality control processes resulting in the ovbious price differences.
The guy in the link below made a great attempt at a DIY project although I think he could have been a little more creative. I still give him kudos for it though and props on using a PC powersupply.
This was the first and cheapest kit I found and now that I'm re typing this at 3:30am I'm definitely not searching anymore tonight.
[Ebay Link Removed]
My only concerns are heat and PAR value of the automotive HID bulbs. Also if anyone has had a chance to test their PAR values or found articles where they have.
I've also read that the CRI rating for HID bulbs is extremely high for those who are interested.