Thanks for the information!
Was it $40 per person in November? I have just looked it up and showing $315 for two adult and one child for July.
This flight is seasonal and generally disappears in late October, reappearing generally in May. The most common alternatives when the nonstop flight is unavailable or very expensive, is to fly Xi'an-Changsha then take train or bus, or take train all the way (which can be lengthy and sometimes requires a switch of trains partway).
Chinese domestic flight system puts the final flight schedule and discounted fares into the system quarterly. For July, anything you are seeing now is the full-fare placeholder. Best to wait until at least May or early June before booking this flight.Edited: 26 February 2018, 00:47
Having said that, July is high season for travel inside China and the discounts you can find might not be all that great. China Eastern is one of two airlines doing the nonstop on this route and the will often put "early bird specials" for their fares, so do start keeping tabs periodically and if you see something you can live with, buy it. Tip: you may be better off buying 3 discounted adult fares rather than fool around with a child's fare which is based on a percentage of the full fare economy ticket.
Thank you kvchinaa.
I'm short of time so will have to fly. I'm actually travelling myself with my two kids but one is 12 years old so I am presuming that he will be adult fare.