I've found good prise to my fly on AirChina DE web**. I've some troubles with data format, but It was, in the end, with paying with my credit card, It was incorrect confirmation of my bank (bank blocked too high payment). You should try your payment in your bank or you can pay in PayPal. Finally I've done in this way, without any problems.
** There was no good prises in others webs of China, even China.CN or others dealers/brokers