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 (12.31 USD): EARSP11
Coupon (12.31 USD): BGAFF10OFF
(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): TTxBG10, aff7off, BG3CSUM, bgssaff9, AFfbG10, 502C6B, BGBFAFF2019, BGCITYADS2019, BGVDay10%off
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for KZ ZS3 Detachable Earphones.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).