It is suggested to go to Guangzhou from Lanzhou first, or to Zhengzhou first, and then to Haikou.
If you go to Zhengzhou first and then Haikou, the price is 150+257=407.
If you go to Guangzhou first and then Haikou, the price is 293+ 106=399.
The fare has been changing. I don't know when you will travel ~ ~