Working humidity: 5 – 95pct, Working Temp.(℃): 0 – 40 Deg.C.
Go down and check coupons out. Remember to check price history if it is available. Let’s see what best price is ATM.
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. ($30.79): BGAFF10OFF
2. ($31.21): BGSAMRTH
just apply this code in your 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): BGAqara, affiliate6, 2019SPEDM, bgssaff9, aff7off, BGaDmITAd, BGBFAFF2019, BGCITYADS2019, 2020CNY, BGAQ20, BGSAMH, BGAQA15, bGhOnEy10, BGSM15, BGSMOFF, bgshOOp10, BGELIG0920, BgcLuBofErtA10
(there’s a little possibility that old coupon will work)
Price history and price alert
Do you need price history chart (for all/most countries) for Xiaomi Aqara Wall Switch ZigBee Version? There we go. The lowest price was: $17.99.
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)).