Go down and check coupons out. Remember to check price history if it is available. 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):
Model: HT-A09-71W Output: 42V~1.7A Input: 100-240V 50/60Hz 2.0A Max Non-rechargeable environment: < -20°C or >40°C Turn lamp current: 100-200mA Cable length: Approx.1.5m Applicable models: Only for Xiaomi Mijia
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
1. ($41.49): BG10OFFAFF1
paste coupon code in your cart and click Apply 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): BgAuMotor, 502C6B, TTxBG10, AM15prime, AMPrime01, Automo, Automo1, BGAutos, bGhOnEy10, BGCARELEC
(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 Mijia M365 42V 1.7A Original Battery Charger? There we go.
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)).