Power supply USB 5V, CO2 detection range Temperature 5-35°C / 400-2000ppm, Detection range of HCOC Temperature 5-35°C / 0~9.999mg/m3, Temperature detection range -10~50°C, Item weight 74g / 2.6ounce, Connection mode Bluetooth4.0, TVOC detection range Temperature 5-35°C / 0~9.999mg/m3, Item size 75 * 75 * 50mm / 3.0 * 3.0 * 2.0in.
Just check coupons out (with price alert and history). 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.
Link: Banggood product page
1. ($18.05): MVC8SPRING
2. ($18.44): BG00c906
apply code in your basket (cart) after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGJAFR996, BGJAXIN996, BGAFF10OFF, BGJATD996, BGDEALJA996, BGFEFO996, BGMRDC31, 13f142, BGAPSE996, BGAPFO996, BGJUFO996, BG10OFFAFF1, 00c906, BGAlerabat1
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Smart USB Bluetooth Air Quality Monitor. The lowest price was: $7.99.
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)).