Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in Europe . There is one coupon available! Pretty cool, huh?
Link: Banggood product page
Coupon (6.87 USD): 2203ActiesNL
(CouponsFromChina.com tip: you should apply the coupon in your 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): BGSmart6, MVC8SPRING, 8BGwbg2204
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for KTNNKG 40A 433Mhz 1Gang 4000W AC90-250V TUYA Switch [EU] is here.
Price records source(s): Banggood
Click on image to enlarge.
You can set price alert (for Banggood).