We have just completed our flight and hotel booking for this year’s China travel. Once again we can conclude that it is cheaper for Chinese than for waiguoren’s (foreigner). As an example, a flight ticket that costs 1030 RMB at the cheapest English web site, costs only 460 RMB at a Chinese web site. This is often the same with hotels as well.
It can be quite a hassle to order flights from a Chinese website though. The workflow goes a little something like this:

This illustration is actually a shorted version of one of our own bookings this year.
In China there are often different prices for Chinese than for foreigners. Often this just goes for the baseline haggle price for peddlers or at open markets, but this difference can sometimes be more explicit. In Hong Kong in 2006, we saw a sign partly written in English, and partly in Chinese. The English described a breakfast menu, with the price at the bottom at 15 HKD. The Chinese part had a similar amount of text, and stated the price at 10 HKD. My wife confirmed that the Chinese section described the same breakfast menu. I really regret that I didn’t take a picture of this.
When we are travelling together in China, my wife and me, we sometime confuse various sellers, by being in two different price categories. I remember e.g. an episode in the Forbidden City where we wanted to buy a map over the place. The seller clearly wanted to sell it to me, because then he could justify selling his map at the foreigner-price. Our interests were obviously divergent, while it was in our interest to let my wife buy it, in order to save the 1 RMB price difference. After a brief discussion we ended up paying the Chinese price, and were free to spend our saved 1 RMB elsewhere.
Some of these price differences can be leveled out by heavy haggling, but this doesn’t go for flight and hotel bookings online. So if you are going to china, it can be a good idea to ally yourself with a Chinese person to assist with the booking.