Battery: 3V(CR2450);, Material: PC;, Dimension: 43X43X14mm, Wireless protocol: ZB (IEEE 802.15.4);.
Just check coupons out (with price alert and history). Do you want to know what the best price is?
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. I’m afraid that there’s 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/i1u
Old coupons (from the oldest to the newest): BG3db1f0, ADMITAD2212, BGd1b582, BGSmart6, BGHU1718, MVC8SPRING, 8BGwbg2204, 2203ActiesNL, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, hoNEYbGdeAlS, BGJUNEGSG9, BG15Sonoff, BG8ReviTrage, Cuponation9, 9OFFSUMMER, COUPONSDE1wk, JanBGCoupon8, BGSaleFeb8, BGSaleAD, BGMARCHSALE, BGAUGUST8, BGCAPITALOS8, BGCOUPERT8, BG8FORMULAMX
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for 10pcs SONOFF SNZB-02-ZB Temperature Humidity Sensor. The lowest price was: $66.6.
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)).