Flight cost Chengdu to Jiuzhaigou

As I know, currently, there are three airline companies operate the flights between Chengdu and JZG and they are Sichuan Airlines, Air China and Southern Airline.
The price for different airlines is hard to tell, because it is easy to get a discount for flight tickets as you know. Whether you can get cheap tickets depends on whether you buy the tickets in advance.
Usually, according to my experience, the Sichuan Airlines has a cheaper price than the others, but not for sure. It is suggested to look for the exact price on their official websites.