For China, Ctrip is not the best price wise. Along with Elong.com, both are decent in price and good for convenience.
If you want rock-bottom prices, Qunar.com is the place.
Qunar will lead to a number of mainland travel agents, most of them cheaper than Ctrip but a lot more painful to buy from :-) To start with Qunar.com is Chinese only. Google translate does help but not 100%. Next pain is the travel agents : Some will demand cash, some will demand Chinese credit card and some just wont want to talk to you if they know you are not internal in China but in the end, if you can navigate thru all that, you wont be able to beat the prices from Qunar.
For those in Hong Kong, I would also recommend looking at travelzen.com ; fairly decent prices but located in Hong Kong and better and more responsive and responsible service.