There is nothing special or new about moon lights. Most any LFS or online fish store should have them. They are usually pretty expensive unless you diy, like all the suggestions above.
Basically put a dim light over your tank. Thats it.
On a big tank some use very small regular flourescent lights, sometimes actinic for the blue look. Most of the time they are LEDs. Sometimes CCFL. Some folks use submersable lights like you'd put in a pond. Most like blue. Moonlight is actually white, 4100K avg though. It doesnt matter for us, use any color you wish. Good luck.