MUSICAL INSTRUMENTS EXPO China (Guangzhou) International Musical Instruments Expo

Hi,
I wish to visit the above exhibition with my brother to buy musical instruments . We are a family of musicians.If we get an invitation by the organizers what type of visa we should apply. And how about other document and fees.This is our 1st visit to China. Can we directly apply visa from the embassy or do we need to contact a travel agency.
Thank you very much in advance!
C.Imalee