Basically copy coupon, view price history or create e-mail price alert. You probably want to know what is the best price?
Wireless Connection Bluetooth 4.2 BLE, Material ABS+PMMA, CMIT ID 2019DP8115, Executive standard QB/WSDJ 2401-2019, Quantity 1Pcs, Voltage DC2.5V- -3V, Humidity range 0%一99%RH, Humidity display resolution 1 %RH, Size 43x43x 12.5mm, Measure range 0°C-60°C, Battery CR2032, Model LYWSD03MMC, Temperature display resolution 0.1°C
Aliexpress
There’re some similar (or not) items on Aliexpress
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. Coupons for 4x Xiaomi Mijia Bluetooth Thermometer Hygrometer 2? Nope, there’re no coupons 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/5cd
Old coupons (from the oldest to the newest): BGNMi2, vipupgrade8, BGKEL2P, BGBFCR02, BGBFCR01, BGDouble11HC, BGTHEMIJIAPL, BGCPDOGI, BGBLACK03, BG5985, BG111BB, BG4Men2, BGMM2, BGHHH2, BGTHERA, BGMiii2, BG2SB2, BG2D2, BG2MFC, BGCXT1, bgshOOp10, BGAFF10OFF, BGHB20, BgoFErTaSchInA10, BG11716, BGUD98, BGXMT5, BGXMR399, BGCC0704, BGMAY06, BG10OFFAFF, BGwhielabel, BGjune95, BGjuly36, BGjuly39, BGxm4pcs, 13f142, BG00c906, BGHealth10D, BGGRJA271, 2022ACTIESNL, BGHU1689, BGITFE111, BGHB218, BGGRMA164, BGHUMA162, BGMAYB231, BGXPAP241, BGHECARE1, 1636677607, BG4ee866, BG61620d, BGHOM001, BGHUXC028, BG69f3a8, BGba5f77, BG8ReviTrage, BG5c3b6b, Cuponation9, BGcbda02, BGf67abb, BG8eca22, BG372dea, BG75597c, BGf7f06c, BG63eef3, BG638642, BG01ec8c, BG4308f7
(probably won’t work, but you can try them out)
Price history and price alert
Here is price history (for all/most countries) for 4x Xiaomi Mijia Bluetooth Thermometer Hygrometer 2.
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)).