Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is no active coupon in my database right now (for 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): BGDT55, bgdt15, band10, BGWRIBAND10, BG8395e2, BG450c1b, BG51f436, BGc70579, BG96c70d
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for DT NO.1 DT55 Fitness Tracker.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).