Surely true for Ali or Gearbest but currently tradingshenzhen sells + or - expensive depending on the currency you use, for example you earn €10 compared to the Chinese price but you lose $10 compared to the Chinese price.I know some famous platform in China are selling at a much lower price than from Official Xiaomi. The reason is that they would resell the returned or fake product. Your case is quite common in China and there is a chance that you are not lucky and get a used phone if you buy from those stores online. In China you can always return the product within 7 days with no reason if you buy from those platforms so those phones that are returned might be resell again as a new one if they look new or not activated, or for whatever reason. My recommendation is to buy from Xiaomi authorized stores online in those platform. I got my 12su from JD platform and the price is the same as the one written in Xiaomi official website since it is equivalent to buying from xiaomi.com. I suspect that tradingshenzhen is one of those stores that sell at lower price in china while they sell at a much higher price in internatinal market.