Was doing a little web surfing a couple of weeks ago and ran into some pretty cool robot eyes. I ordered two 8x8 LED's and with my Arduino, programmed the chip to run them.

Once the eyes are programmed the way you want, then all that needs to be done is pop the chip from the Arduino and make a small stand alone board. Nothing hard at all in this setup. I bought the LED's in a kit and soldered them up but if you prefer you can buy them pre-built. The Arduino stand alone board is just a couple of small components and that's it.

I'd say $15, $20 at the most to build.

Note: *** The above video was found on the net. ***