I just want to find a used copy to be honest for $150-250 but there is none on ebay or amazon, so I wonder if there license even allows a transfer or not.
It's allowed as far as I know.
Check here, perhaps he still has his license;
http://www.zbrushcentral.com/zbc/showthread.php?t=58194&highlight=selling+zbrush
Also very useful, the official resellers;
http://www.pixologic.com/resellers/
