You can still get a buyer badge right at the expo pavillions when you come to China. In this case you'll have to pay 100RMB for it. You should be ready to fill in a form and provide all the docs mentoned above.
If you have got a Buyer card, please pay attention to the following information: The Badge is valid for multiple sessions of the Fair, which ensures your entrance to the Fair directly and saves your time with an easy access. If you forgot to bring or lose it, re-application will cost you 200 RMB/card as service fee. The previous badge will be invalid right after re-application, please ensure the badge you wear is the newest.