$20.99 – Smart Tuya Zigbe WIFI Airbox CO2 Formaldehyde VOC Detector Temperature Humidity Sensor App Control Smart Home Scene Linkage Work with Amazon Google Assistant – Zigbee.
When I was updating this page, then coupon price was $20.99 for Smart Tuya Zigbee WIFI Airbox CO2 Formaldehyde VOC Detector (in Banggood). Price history, coupons and price alert are available on this page. Do you want to know what the best price is?
Latest coupon code price check (UTC time):
Banggood ($20.99)
Banggood warehouse is located in China. There are no coupons available at this moment in Banggood. Is it cheap? It looks like it’s a good price (lower than average ($22.59)).
Link: Banggood product page
Price: $20.99
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BG977107
(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
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
Check out price history chart (for all/most countries) for Smart Tuya Zigbee WIFI Airbox CO2 Formaldehyde VOC Detector. The lowest price was: $19.99.
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)).