It was actually a pretty simple build. They're actually standard (I don't remember the exact type) LED 3mm or 5mm prewired lights (the ones with resisters already soldered and seal to each light) I bent, a small circuit board a friend of mine programmed to make it them fade in and out (you can easily skip this step, it's optional and I wanted to make them blink/fade in and out) and a battery pack. I use a smaller battery pack for LR41 "watch" batteries but that can easily be switched to a 9volt battery connector and battery. I suggest adding a toggle switch if your going with the 9v or a battery pack without and on and off switch.
Cost about $10 to make (minus the circuit board since it was a small trade, He made the circuit board and I made him a set of eyes as well. So it was a win win, he uses his set for in an ODST helmet.)
If you don't feel like making them, some people sell them on eBay under "haunted eyes" or LED haunted house prop eyes (hence why I call mine Ghoul eyes) and in different colors. Either way it cost about the same but I wanted to make them myself as a nice project.
