United, Delta and Air Canada are currently offering flights from Chicago (ORD) to Beijing for ~$400. It looks like travel is for late February through April. I tested Feb 24 -27 and was able to see fares from United for $389. I should note that these flights were not booked into basic economy so you should be able to check a bag for free on all three airlines.
I should note that flights from Delta and Air Canada will not be direct. The Delta flights will connect through either Seattle or Detroit while the Air Canada will connect through Toronto or Vancouver.
Reminder: If you want to book this flight make sure that you have a Chinese Visa. A 10 year Visa costs about $140.