There is MRT from guangzhou Bai yun to guangzhou east railway station. This is a good alternative route to changping if you don't want the hassle of clearing customs when you land in HK.
From Guangzhou Baiyun to changping. take mrt to GZ east railway then change to bullet train to CP , whole trip less than 2 hours, if fast 1.5 hours. cost? I think it's 14RMB for MRT and 55 for bullet train, total less than 70 RMB.
