You can create price alert here, copy coupons and view price history. You probably want to know what is the best price?
Phone Take Photo., Oxygen Saturation Monitoring., Overseas Model Supports NFC., 5 Sport Modes., Larger Screen., Amazon Alexa Voice Assistant.
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.
Link: Banggood product page
1. ($42.58): BAND10
2. ($42.58): band10
3. ($42.58): BGWRIBAND10
apply code in your basket (cart) 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): BGMI5CN, BGMB5CN, BGM5CNDE, BGM5JUL, BGM5HKJ, BGSS10%SW, BGM5NCN, BGMCN, BG08BAND5C, f40998, bgshOOp10, BGUSAM5, BGM5FE, BGDQM5C, BGDQM5USA, BG11SHOP, BGCuponation10, BGMI523, BGMIBAND5, BGcf76cd, BGG46510, BGWRIBGcca560, BGd5878e
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Mi Band 5 Smart Watch CN.
Price records source(s): Gearbest, 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)).