Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (29.44 USD): BGHB218
Coupon (32.56 USD): BG00c906
(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): BGBFAFF2019, BGHW2, BGCare2, vipupgrade8, 0e7f33, BGHB20, BGSD52147, 13f142, BGCuponation10, BGHONEY2110, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BANGGOODSD, BGHealth06, 00c906, BGHealth10D, 2022ACTIESNL
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Jeffbona Hand Warmer 3600mAh.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).