catch a train or bus from Kunming to Haikou(Details?)which alternative is better(cost vs time)

In the East Coach Station, there is a bus leaving at 11:00. The bus fare is CNY500 and the travel time is about 24 hours.
There is no direct train, you are suggested to take a flight, which takes about 2 hours. The air fare is not fixed but different according to the travel time. You should book the tickets in advance.