$21.99 – Output current: 90mA, Weight: 0.235Kg, Features: soft touch design / programmable, Display: LED data display, Voice control: Alexa google home, Temperature range: 5~35°C, Temperature measurement error: 0.5℃, Model: ZTRV-ZX-TV02-EN, Dimensions: 105x 90x 70mm, Name: radiator valve switch, Working voltage: 1.5V.
According to my DB the lowest price is $21.99 for Tuya ZB Smart Home Radiator Valve (in Banggood). Basically copy coupon, view price history or create e-mail price alert. Do you want to know what the best price is?
Latest price update (UTC time):
Banggood ($21.99)
Banggood warehouse is located in China. Too bad there’s no coupon right now in Banggood. Good or bad price? This price is great, coz it’s the lowest in CouponsFromChina database!
Link: Banggood product page
Price: $21.99
Additional Banggood coupons: first page and second page
This is the best price ever noted in my database!
Old coupons (from the oldest to the newest): ADMITAD2212, BGSmart6, 8Couponsde, MVC8SPRING, 8BGwbg2204, 2203ActiesNL, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, hoNEYbGdeAlS, BGJUNEGSG9, BG8ReviTrage, Cuponation9
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Here is price history (for all/most countries) for Tuya ZB Smart Home Radiator Valve. The lowest price was: $21.99.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).