I have just checked coupons. The lowest price I could get is 55.99 USD for Smart Thermostat Wall (in Banggood). You can create price alert here, copy coupons and view price history. Let’s see what best price is ATM.
Latest price update (UTC time):
Banggood (55.99 USD)
Banggood warehouse is located in China. I don’t think there is an active coupon right now – at least in my database. You probably want to know if this is a good price. Well, this price is higher than average price (53.66 USD)
Link: Banggood product page
Price: 55.99 USD
There were country-specific coupon codes published on Couponsfromchina social channels and price alerts. Coupon price may vary by country, because there’re different VAT rates, shipping cost etc. There is a chance that some latest coupons are still working:
Coupon (20.3.2024, $50.99): BGSSCO001
Item: SONOFF NSPanel WiFi Smart Thermostat Wall Switch White
Countries: Austria, Belgium, France, Germany, Italy, Luxembourg, Netherlands
Coupon (20.3.2024, $50.99): BGSpring107
Item: SONOFF NSPanel WiFi Smart Thermostat Wall Switch White
Countries: CzechRepublic, Hungary, Portugal, Slovakia(SlovakRepublic), Slovenia, Spain
Coupon (20.3.2024, $50.99): BGRMARSO03
Item: SONOFF NSPanel WiFi Smart Thermostat Wall Switch White
Countries: Greece
Coupon (17.3.2024, $50.99): BGspring107
Item: SONOFF NSPanel WiFi Smart Thermostat Wall Switch White
Countries: CzechRepublic, Hungary, Portugal, Slovakia(SlovakRepublic), Slovenia, Spain
Old coupons (from the oldest to the newest): BGb0d0b9
(probably won’t work, but you can try them out)
Aliexpress
Click here… to search for SONOFF NSPanel WiFi Smart Thermostat Wall Switch White on Aliexpress
Here are coupons that you can use.
Price history and price alert
Here is price history (for all/most countries) for SONOFF NSPanel WiFi Smart Thermostat Wall Switch White.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).