Xiaomi ClearGrass Air Monitor (Banggood, Aliexpress: Specification Wireless network: Wi-Fi IEEE802.11b / g / n2.4GHz, Battery capacity: 2000mAh / 3.7V, Battery type: lithium ion battery, Weight & Dimensions Product weight: 0.2170 kg, Power connector: USB-C, Package weight: 0.3000 kg, Rated input: 5V 1.5A (the best price with coupon)).
Price history, coupons and price alert are available on this page. You probably want to know what is the best price?
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.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood.
Link: Banggood product page
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/feV
Old coupons (from the oldest to the newest): BGherra, 7d18f7, BG11SHOP
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Do you need price history chart (for all/most countries) for Xiaomi ClearGrass Air Monitor? There we go. The lowest price was: $109.99.
Price records source(s): Gearbest, 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)).