Flights from Toronto to Beijing and Shanghai, China just experienced a 25-30% price drop below their usual bottom price.
These fares to China look to be available on a large variety of dates between September 2013 and March 2014.
Use Kayak.com to find the best availability: http://www.kayak.com/flights/#/YYZ-PVG/2013-10-27-flexible/2013-11-06-flexible
Look for the flights on United with 1 stop each way in Chicago or Newark. The total travel time should be around 16-17 hours each way.