Where is this Huanghe clothing wholesale market in Dongguan.

Hi, it is located on Yinlong Road, Humen Town. It is near the Humen Avenue in the south and Humen Square in the west.

If you take a train from Guangzhou East to DG, your dropping-off station is still around 31mi to the clothing wholesale market. Then you need to transfer several times by local bus to get there. By taxi, you need to spend CNY130-150.

Well then, I have a better suggestion for you:
take Guangzhou subway line 1 at Guangzhou East to Gongyuanqian, where transfer to line 2 to Guangzhou South. There you can take a high-speed train to Humen. Upon getting there, the clothing wholesale market is only around 3.8mi away, so you can take a taxi to reach.