Sorry that this happened to you.  
Hong Kong's postal system went down hill since 
Mainland China took over the government.  It is one 
of the worse places to send letters to.  Many of my 
friends sent payment to there that never arrived.  
It doesn't matter whether it's registered or global 
priority; it's still subject to being stolen.  My 
suggestion is that in order to protect your money 
that you send to Hong Kong, always send it Express 
mail; it's insured and trackable.  

As far as the jerk that stole your money goes, you 
have up to 90 days to leave him a negative on Ebay.