Aliexpress
Here are coupons that you can use.
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – BlitzWolf BW-SS10 3000W Smart Water Heater Switch [EU] (-3 USD)
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
Coupon (14.55 USD): Cuponation9
(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): BGSHOM15, BGSHE15, 13f142, BGcou461, BGc39da0, 6GSGIT, BG3d2d6d, BG53c5d3, BGD11017, BGB5017, BGe31f66, BG93f92f, BG128aa3, BGd005ff, ADMITAD2212, BGSmart6, BGd5b9d3, 8Couponsde, MVC8SPRING, 8BGwbg2204, BGJUNEGSG9, 9OFFSUMMER
(probably won’t work, but you can try them out)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – BlitzWolf BW-SS10 3000W Smart Water Heater Switch [EU] (-3 USD)
Price history and price alert
Here is price history (for all/most countries) for BlitzWolf BW-SS10 3000W Smart Water Heater Switch.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).