Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. As you can see I didn’t find any active coupon for this product right now…
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): 502C6B, RBT21, TTxBG10, AFfbG10, BGT21, BGRT21, BGBFAFF2019, BGCITYADS2019, 13f142, BGVDay10%off, EARSP11, BGAFF10OFF, bGhOnEy10, BGSS10%SW, bgshOOp10, BGELIG0920, BG11SHOP, BG4BW25, BGLOAC1, BGa0b145
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for Remax RB-T21 Mini Bluetooth 4.1 Earphone is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).