You can get Tuya WIFI Smart CO2 Meter TVOC PM2.5 PM1.0 for $117.75 with coupon (from Banggood). Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
Tuya WIFI Smart CO2 Meter TVOC PM2.5 PM1.0 Temperature and Humidity Infrared Sensor Air Quality Monitor – With EU smart socket
Latest price update (UTC time):
Banggood ($117.75)
Banggood warehouse is located in China. The question is – is it a good price? This price is higher than average price ($106.09) for this item. You can get coupon down below.
Link: Banggood product page
Price without coupon: $127.99
1. ($117.75): BGALL8
you should apply the coupon in your 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
Old coupons (from the oldest to the newest): BG20236Tool, BG183b9c, BGTOOS729, BGBFDAY8
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
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
Check out price history chart (for all/most countries) for Tuya WIFI Smart CO2 Meter TVOC PM2.5 PM1.0.
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)).