Hope this helps a little!! 
Can you please further explain what a void coin is?
Void coins different and rarer than the demo coins
These were coins made for interviews Mike did. These surface very very rarely.... Mintage I really dont know. But its low. I dont know whether that means 1's or 10's. But I have never seen anything stated. I have only ever seen 2 for sale. Missed the first, and traded for the second one
Mike mentioned them on his Wordpress
https://casascius.wordpress.com/2013/05/19/casascius-coin-production-featured-in-the-rise-and-rise-of-bitcoin/
No one has asked this yet, but I am also seen making some coins. As my security policy totally prohibits creating real coins on camera, these coins do not contain real private keys instead the paper shows the word VOID in bold, very clearly, through the window. I call them voidcoins or presscoins, as I allow the photographer to keep one or two of the completed ones if they wish. All such coins are 0.5 BTC denomination.
These were coins made for interviews Mike did. These surface very very rarely.... Mintage I really dont know. But its low. I dont know whether that means 1's or 10's. But I have never seen anything stated. I have only ever seen 2 for sale. Missed the first, and traded for the second one
Mike mentioned them on his Wordpress
https://casascius.wordpress.com/2013/05/19/casascius-coin-production-featured-in-the-rise-and-rise-of-bitcoin/
No one has asked this yet, but I am also seen making some coins. As my security policy totally prohibits creating real coins on camera, these coins do not contain real private keys instead the paper shows the word VOID in bold, very clearly, through the window. I call them voidcoins or presscoins, as I allow the photographer to keep one or two of the completed ones if they wish. All such coins are 0.5 BTC denomination.