If you paint the design and put LEDs in, the "power" will probably come out darker than the surrounding plastic. From the reference pic, it looks like the cross hairs are supposed to lighter, but I'm not sure how picky you're going to be about that.
Your better bet for that is probably etching acrylic
, as putting an LED on the side of that would give you pretty much exactly the effect you're going for. If you're not into the idea of dremeling (or don't have that tool around), I'm pretty sure there are places online where you can order laser-cut parts, so you could just draw it out and pay to have someone else cut the lens/do the etching for you.
Another thing to think about is the orange tint that'll already be on the goggles. Adding blue to it isn't going to wash out that color; you're gonna get some intermediate.
Also, in thinking about wiring, you'll definitely need some sort of power source-- maybe a small watch battery? You could hide the battery clip under your wig pretty easily (if you're using one).