Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (493.99 USD): BGbea73b
Coupon (493.99 USD): BGB5052
Coupon (496.99 USD): BG7d8cff
Coupon (574.99 USD): BGc27462
Coupon (624.10 USD): BG4a7a54
(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): 13f142, BG11f772, 6GSGIT
(probably won’t work, but you can try them out)
Price history and price alert
Do you need price history chart (for all/most countries) for Xiaomi Automatic Smart Door Lock Pro XMZNMST03YD? There we go.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).