Aliexpress
Click here… to search for Xiaomi Drone Battery Fast Charger on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
Coupon (60.55 USD): Parts8
(CouponsFromChina.com tip: 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
Old coupons (from the oldest to the newest): aff7off, TTxBG10, bgssaff9, AFfbG10, 502C6B, BGBFAFF2019, BGCITYADS2019, 0e7f33, BGMPB2020, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, bgshOOp10, BGRC902, BgoFErTaSchInA10, BgcLuBofErtA10, 7d18f7, BGCuponation10, BGDAVIS, BGHONEY2110, BGquadpart
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Drone Battery Fast Charger.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).