Aliexpress
Click here… to search for Xiaomi Mi MIX 3 5G 6/64GB Global Blue on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in Hong Kong.
Link: Banggood product page
Coupon (329.99 USD): BGM35G
Coupon (359.99 USD): BGCITYADS2019
Coupon (371.99 USD): od7off
(CouponsFromChina.com tip: just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGMIX35G, BGaDmITAd, BGBFAFF2019
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Do you need price history chart (for all/most countries) for Xiaomi Mi MIX 3 5G 6/64GB Global Blue? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).