http://www.yoee.com/default.asp

This is basically a discounter for all of the Chinese airlines. You can buy your tickets through them directly but it isn't as straightforward as buying tickets online here in the US. You'll get through it fine if you read Chinese.

The Chinese government officially controls airfares and "officially" limits the amount of discount a given airline can offer to passengers. Yoee website is the only one I have ever found that breaks this and sells the tickets at a larger discount... at times they sell at 30% of published Y fares, but normally it is 50-70%.

There are 2 airports in Shanghai. Pu Dong is the larger international airport and Hong Quio is the domestic airport. You may have better results from one airport or the other. Pu Dong has Maglev train transport into the City, but to Hong Qiao you'll have to rely on Bus or Taxis.

I just pulled a sample round trip from Pu Dong to Beijng capital on Apr 1 returning on Apr 8 and I came up with 1,020 Yuan before taxes, that's about $127. Taxes don't amount to a whole lot of money on top of that.

Hope this helps...