Go down and check coupons out. Remember to check price history if it is available. Best price?
Material: Silicone, Type: AMOLED, Resolution: 360*360pixels, Bluetooth Version BT 5.0, Length: about 200mm, Battery Capacity: 390mAh, Width: about 22mm, Charging Type: Magnetic charging, Size: 1.3 Inch, Using time: About 20days, Standby Time: About 66days, Charging Time: About 2hours, GPS+GLONASS Support
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
1. ($152.95): bgwp
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGTREX, BGTR132
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Amazfit T-Rex CN Smart Watch.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).