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 (8.97 USD): BG589b2e
(CouponsFromChina.com tip: apply code in your basket (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): ADMITAD2212, 2022ACTIESNL, Terence, Tabby20, 8Couponsde, MVC8SPRING, 2203ActiesNL, BG00c906, BGJUNEGSG9, Cuponation9, 9OFFSUMMER
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Price history (for all/most countries) for XXD HW40A 40A Brushless Motor ESC is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).