Here's two links that are incredibly useful if you're electronics savvy to make a bucky skull talk with a servo motor and a (rather complicated) circuit:
Install a Servo in a Bucky Skull
Scary Terry Audio Driver
I built two of them last year to make my poker-playing Grim Reapers. The circuit is a pain to make on the prototype boards from Radio Shack, so I'd strongly urge you to just buy a kit from Cowlacious. I'd have done that if they were making them last year.