Hrmm, not sure about the shipping; I neglected that little detail that says you are in China. I would say to just buy it from that place in beijing, because shipping from the US to China is an ass-fucking. Save up a little money and just buy it in bulk, the initial investment sucks, but at least you don't have to hunt for protein when your favorite store stops carrying the stuff you like (ala Sam's or Wal-Mart).
When I order from Trueprotein, I usually get it at 10lbs a time. Last order, I bought 25lbs and it lasted me about half the damn year, lol.
Basically, the more you buy, the cheaper it is. Just be sure that when the shipment comes in, you have plenty of Ziploc freezer bags to store it in, as it comes shipped in a giant trash bag.