Hi
I haven't personally traded with DHGate but there is quite a lot of information and advice on these forums for you to check out. Mostly the advice I have read is if it's really cheap it is likely to be a copy, Jimmy offers some good advice as to how to go about checking as best you can product quality, if you do a forum search you should be able to find it. Also the general advice is if you are thinking about dropshipping you should try and buy a sample yourself, no doubt you would be able to tell the difference between a fake and the real stuff.
Regards
Tab