Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (18.99 USD): BGc94210
Coupon (36.54 USD): BGTS666
(CouponsFromChina.com tip: coupon code has to be applied in shop’s cart 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): BGwhielabel, 13f142, BG10OFFAFF1, BGba7bf6, BG3caf1e, BG8b1335, BG4e47f0, BGAlerabatdo, BGf8ec36, BG3bd340, BG716337, BG7f1811, BG267e3b, 2022ACTIESNL, Terence, BG1efeb0, MVC8SPRING, 8BGwbg2204, BG9f0c54, BG31483b, 8wEbgaInS5, pROMo8cuPoN, BG397e35, BGe6e89b, BGHOM119, BGsmartbuyU1
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Price history (for all/most countries) for HIPEE Smart Back Posture Corrector is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).