If Canada Post does not offer Signature Confirmation of Delivery to China, go to the various couriers and see if they will.
DHL handles a lot of traffic from China, so perhaps starting there?
Did you have a price for shipping to China in your listing? If not, don't do anything until you do have a firm price with SC.
If the bidder purchased without a firm quote on shipping, YAAAY!. You can give him a fair price, with Air Mail and Signature Confirmation, after he wins. EBay will back you on the price. (Don't go nuts on this, obviously. Be fair.)
As for shipping restrictions-- China has no Rule of Law. Which means that such laws as there are, are randlomly enforced and new 'laws' appear at the whim of the enforcers. Your buyer may have to bribe the delivery guy to get his package. It could be restricted but no one cares. It could be seized and returned and then the next delivery goes through without a whisper.
