Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in Hong Kong.
Link: Banggood product page
Coupon (17.99 USD): BG8a509b
Coupon (40.24 USD): BGc70579
(CouponsFromChina.com tip: paste coupon code in your cart and click Apply 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): band10, BGWRIBAND10, BGb58412, BG51f436
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for UMIDIGI Uwatch 3S Fitness Tracker.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).