According to my DB the lowest price is $31.04 for Tuya WiFi Temperature Humidity Sensor With LCD Display (in Banggood). Price history, coupons and price alert are available on this page. You probably want to know what is the best price?
Tuya WiFi Temperature Humidity Sensor With LCD Display Smart Life Remote Monitor Indoor Thermometer Hygrometer Via Google Alexa
Latest price update (UTC time):
Banggood ($31.04)
Banggood warehouse is located in China. I don’t think there is an active coupon right now – at least in my database. Price? From what I can see this price is higher than average price ($16.97).
Link: Banggood product page
Price: $31.04
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG589b2e, BGb05e60
(I don’t think these’re gonna work, but you can try ’em 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
Price history (for all/most countries) for Tuya WiFi Temperature Humidity Sensor With LCD Display is here.
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)).