Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in Hong Kong.
Link: Banggood product page
Coupon (112.49 USD): amazfit100
Coupon (119.99 USD): 7d18f7
(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): BGGT42M, BGGTR42, AFfbG10, 8fbade, bggtr128, BGGTR129, BG11GTR42, BGGTR42119, BGGTR42JL, BGGTR109, BGGTR100, BGGTR11499, BGALIBUYTR, BGALIBUYAGT, Email5, BGFabioamaz
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Do you need price history chart (for all/most countries) for Xiaomi Amazfit GTR 42mm Smart Watch? There we go.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).