When I was updating this page the price was $18.99 for Tuya WiFi Smart Temperature Humidity Sensor (in Banggood). Just check coupons out (with price alert and history). What is the best price?
Latest price update (UTC time):
Tuya WiFi Smart Temperature Humidity Sensor Indoor Thermometer Hygrometer Meter with LCD Display Screen Detector APP Remote Monitoring Support Alexa Google Home
Banggood ($18.99)
Banggood warehouse is located in China. Hmmm… There is no active coupon in Banggood at this moment. Good or bad price? Hmmm, price is higher than average (which is $18.83 right now), so better set price alert down below…
Link: Banggood product page
Price: $18.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG1bba93
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Aliexpress
There’re some similar (or not) items on Aliexpress
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 WiFi Smart Temperature Humidity Sensor.
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)).