Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. There are no coupons for this product in Banggood.
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): 99huawei3, 502C6B, e2bcea, band10, TTxBG10, BG3CSUM, AFfbG10, BGHW3, BGBFAFF2019
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Huawei Band 3 Pro Smart Watch.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).