Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (53.99 USD): BGAFF10OFF
Coupon (53.99 USD): bGhOnEy10
(CouponsFromChina.com tip: coupon code has to be applied in shop’s 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): BGToolkitRC10, affbg10, AFfbG10, 502C6B, BGCITYADS2019, BGVDay10%off, BG10BC, BGMPB2020
(there’s a little possibility that old coupon will work)
Price history and price alert
Here is price history (for all/most countries) for ToolkitRC M8 DC 300W 15A RC Battery Charger White With Power Supply.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).