When I was updating this page the price was $20.99 for Smart Tuya Zigbee WIFI Airbox CO2 Formaldehyde VOC Detector (in Banggood). Get coupons, create price alert or check price history out! Let’s see what best price is ATM.
Latest coupon and price update (UTC):
Smart Tuya Zigbe WIFI Airbox CO2 Formaldehyde VOC Detector Temperature Humidity Sensor App Control Smart Home Scene Linkage Work with Amazon Google Assistant – Zigbee
Banggood ($20.99)
Banggood warehouse is located in China. What about the price? Actually this is the best price in history according to CouponsFromChina database! There is one great coupon!
Link: Banggood product page
Price without coupon: $21.99
1. ($20.99): BG977107
apply code in your basket (cart) after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
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 Smart Tuya Zigbee WIFI Airbox CO2 Formaldehyde VOC Detector.
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)).