The type of lighting depends on your organisms. Since you may not know yet what kind of organisms you will end up with, plan on using PC (power compact) or VHO (very high output) fluorescent with the possibility of adding Metal Halide (MH) later if you decide to have acropora and/or clams.
There are some advanced discussions regarding DIY VHO here on the board. Ballasts are available at Commercial Lighting here in SLC but the tubes must be purchased from the LFS or mail order. (this is where the mirrored aluminum spoken of in another thread is such a good DIY deal)
Natural sunlight can give the light that MH tries to duplicate. I'm waiting to hear of someone placing a large tank in the window or using a "light tube" to bring sunlight to the tank!
Now you're probably wondering between PC and VHO. PC are more cost effective but VHO can bring out some great color in the coral and algae. www.garf.org uses VHO. Check out their images.
For those reading this that are not able to afford these expensive lights, ordinary fluorescent lights can do great things. Check out my old tank pictures in the wesite "Gallary" I had six ordinary 40 Watt tubes over that tank. Four actinic, one white and one plant grow tube for bringing out the color (helps grow coralline algae too).
Mark