non-condensing, Battery Mode CR2450, Examination Range 0-83000lux, Wireless Protocol Zigbee 3.0, Working Temperture -10℃-50℃, Model GZCGQ01LM, Working Humidity 0%-95%RH.
Just check coupons out (with price alert and history). 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 coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. One coupon is available. Cool!
Link: Banggood product page
1. ($16.68): BGSmart6
apply code in your basket (cart) after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGXMLS, BGSAMH, BGXML, bGhOnEy10, BGXMLSG, BGSM15, 13f142, BGSMOFF, bgshOOp10, BGSAMRTH, BgcLuBofErtA10, BGXMLIS, BG15SH12, BGSTHO15, BGAFF10OFF, BGXMMIJIA02, BGHONEY2110, BGSHOM15, BGSHE15, BGCL608, 6GSGIT, BG4c7991, BGD11041, BGB5048, BG58566a, BGfeb851
(these codes were not working in latest coupon update, but you can check them out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – Xiaomi Mijia Zig Bee 3.0 Smart Light Sensor [EU] ($-3)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi Mijia Zig Bee 3.0 Smart Light Sensor. The lowest price was: $9.99.
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)).