A lot of times the price those small websites quote initially is the price "pre-tax" which ends up being significantly cheaper than what you will actually pay, in the end. There's all sorts of federal (even internationally) taxes on planes, stuff like airport usage fees (each airplane has to pay so much to land), and so on, that gets lumped in.
I was able to fly to Shanghai from Chicago last March for around $700 (total), which is about as good as you can typically find -- I think. It really depends on where you are flying into. In most cases, flying into Shanghai, Beijing, or Hong Kong is going to be considerably cheaper than anywhere else. Legend has it that some of the air carriers will sometimes offer ridiculously low rates, on the order of $400 round trip, etc. But I have yet to find such a rate in my own explorations. ;-)
To contrast, the best rate I could scrounge up from the states to Guangzhou this summer was about $880 -- and that was flying out of NYC-JFK or LAX.