Adolph Dassler, founder of Adidas was an ardent Nazi who signed his letters "Heil Hitler". Coincidence? I think not.

Instuctibles has a tutorial to make a video version of these for $40. I have absolutely no knowledge of electronics and I put them together in less than an hour. Only works if you are outdoors, although I suppose you could carry a white cane if you need to shoot indoors.

http://www.instructables.com/id/Covert-Spy-Sunglasses/