Here's a list of the art fairs happening in September:

20/21 British Art Fair
Royal College of Art, Kensington Gore 
The best fair for modern and contemporary
 British art
Sep 11 - 15, 2013

SH Contemporary Fair
Shanghai Exhibition Center
SH Contemporary Fair hosts modern and contemporary galleries
Sep 13 - 15, 2013

Expo Chicago
Navy Pier, 600 East Grand Avenue 
The International Exposition of Contemporary/Modern Art & Design
Sep 19 - 22, 2013

Art Platform - Los Angeles
A contemporary and modern art fair committed to the growth of greater Los Angeles as an international art capital
CANCELLED