Xiaomi Aqara Single Smart Switch International (Banggood, Aliexpress: Wireless Type Zig.Bee, Size 86*86*15.12 mm, Battery Life About 2 years, Work Temperature -5℃-50℃, Work Humidity 5%-95%RH (the best price with coupon)).
Price history, coupons and price alert are available on this page. 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 code price check (UTC time):
Banggood
Banggood warehouse is located in China. Well, there is one coupon available right now.
Link: Banggood product page
1. ($15.99): 13f142
this code has to be applied in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/feV
Old coupons (from the oldest to the newest): Alibuy91173, 2019SPEDM, aff7off, bgssaff9, BGaDmITAd, bgchinafest, BGBFAFF2019, BGCITYADS2019, bGpAnDacHeCk, 2020CNY, BGSAMH, BGAQA15, bGhOnEy10, BGSM15, BGSMOFF, bgshOOp10
(you can check these old coupons out, but these probably won’t work)
Other warehouses/versions
This item is available in 2 another warehouse/versions!
1. China – Xiaomi Aqara Double Smart Switch International ($-3)
2. Europe – Xiaomi Aqara Single Smart Switch International [EU] ($-3)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Aqara Single Smart Switch International. The lowest price was: $12.49.
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)).