Where can I find a human skull og in terms of breaking strength?

As close to (preferably the same make as) the one the Mythbusters used in the second James Bond special when they tested the steel dentures of the henchman Jaws. Any sources where I can find it is acceptable, but I don't want just an anatomical model, I need to break it and be able to use it as a gauge for how much abuse a real human skull could withstand.