It is too far from Beijing to Guanzhou and the best way is to take airplan betweem them. The airfare changes frequently and the curent lowest airfare is about CNY1330(US$205). You'd better check the following website to find the accurate rate for the flight: https://www.travelchinaguide.com/china-flights/ . Aside from Guangzhou, you can also go to visit Shenzhen, Hong Kong, Macau or Zhuhai near to Guangzhou.