If you can negotiate the Chinese the best site is qunar.com for domestic tickets. Ctrip if you need English though elong.net has been better of late. For international tickets Kayak is the best site. Sadly gone are the days of paying on delivery. Good luck.

@ Alpage48

Were you comparing an international flight when you came up with your differential, or just one of China Eastern's own flights?

@tigertiger,
I was comparing the SAME flight - Kunming to Chengdu. I even checked the flight number to make sure it was the same one. I expected the rates to be close, but they weren't.

@AlPage48

You are quoting for an internal/domestic flight. For internal flights we do NOT use Xpedia. For the reason you stated.

The OP's enquiry was about international flights, which is a different market sector. For international flights we use Xpedia.