Basically copy coupon, view price history or create e-mail price alert. Best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Note: due to the different production batches, Please download APP “Smart Home” from the Apple Store or Google Play, Temperature detection range: -20 – 60 Deg.C (+ / – 0.3 Deg.C), Powered by a CR2032 button cell (included), Humidity detection range: 0 – 100pct RH (+ / – 0.3pct), Atmospheric pressure detection range: 30 – 110KPa (+ / – 120Pa), there are two different ty
Banggood
Banggood warehouse is located in Europe 
. Sorry, but there’s no price history in my database.
Link: Banggood product page
1. ($13.66): BG86f8e3
2. ($15.99): BGcou931
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): 20XMAQ, d173d2, 950fd5, BG10AQTH, 2019SPEDM, BG9AQTH, aff7off, bgssaff9, BGAqara815, BGPLATMOS, BGaDmITAd, BGAQTH09, 13f142, BGplatmos9, BGBFAFF2019, BGCITYADS2019, BGAQT91, BGATMOS, BGAQ20, BGXMTH02, BGHOMEAPP, BGSMARTHO, BGAQA15, bGhOnEy10, BGSM15, BGSMOFF, BGAQTH7, BGAQTE, bgshOOp10, BGSAMRTH, BGXM1SND, BgcLuBofErtA10, BGAQTEMP, BGAQTHSP, BGAQTHSE, BGAQTHP, BGAQTECZ, BG12AQ2345, BGAQTPP, BG15SH12, BGSTHO15, BGAFF10OFF, BGAQTUK, BGCuponation10, BGAQTASS, BGfdc1b3, BGHONEY2110, BG87ba34, BGff59b6, BGSHOM15, BGcc8c15, BG9bbcd8, BG92e8e9, BGa99dee, BGdf29fc, BGSP316, BGSPC316, BGISOG316, BG687e63, BG579bf1, BGCL1316, BGHO316, 6GSGIT, BG600600, BG7c6a6d, BGb0039f, BGD11046, BGD11316, BG8b53f8, BGB5058, BG317294, BGSmart6, MVC8SPRING, 8BGwbg2204, 2203ActiesNL, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BGJUNEGSG9, Cuponation9, 9OFFSUMMER
(these codes were not working in latest coupon update, but you can check them out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. China – Xiaomi Aqara Temperature Humidity Sensor ($-3)
Price history and price alert
There is only one database record (it was for $13.99), so you can’t see price history chart.
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)).