I wouldn't bother. Go read their "About" page:http://www.gpdxd.com/about-us/
It's just full of corporate jargon and keywords.
If this is the same site another thread had mentioned a while ago the site looks like it's run by another store, Willgoo, but just for the XD.
If you want the safest option, go to Amazon/Aliexpress and find either GPD/GPD Shenzhen, respectively. Their are the manufacturer's stores.
Otherwisr their is GeekBuying, Willgoo, DinoBest, GearBest, etc... All have relatively mixed reviews. I got mine from Willgoo and it works perfectly, but I went with the cheap shipping and it took 50 days to arrive. Go with DHL or whatever whichever you choose.
Amazon or Aliexpress are your safest options.