They're just corrupt thieves.
They're thieves. After the products arrive at their warehouse, they start charging inexplicable extra fees to allow you to ship them. Shipping to their warehouse cost me $42. When I wanted to ship them to another warehouse in China, they asked for $96. They placed the shipping order and charged me the fees without explaining why. I asked to cancel the shipping order and place it manually. According to their shipping calculator, this cost me $106, which I paid to be done with it. Then they charged me an additional $48, and I have no idea why! They said they wouldn't ship if I didn't pay the extra fee. Now the shipment is with them, and I refuse to pay any more. They're just corrupt thieves.