The only way to get the buyer card is go to registration office personally . Pre-register(invitation) online will save you time and money when get to registration office.
Here are registration Offices set up in appointed hotels to get the buyer card(badge).
Registration time of these hotels:
Apr. /Oct.14-15, 8:30-20:00
Apr. /Oct. 16-17, 8:30-18:00
Apr. /Oct.22-23, 8:30-18:00
Apr. /Oct.24, 8:30-18:00
In Spring: Apr. 30-May 1, 8:30-18:00; May 2, 8:30-14:00
In Autumn: Oct. 30-31, 8:30-18:00; Nov.1, 8:30-14:00