Aliexpress
Click here… to search for DALRC ENGINE 40A Pro 3-5S RC ESC on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. Well, there is one coupon available right now.
Link: Banggood product page
Coupon (73.31 USD): Parts8
(CouponsFromChina.com tip: 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
Old coupons (from the oldest to the newest): BGDL40, AFfbG10, BGWKEG40, BGGEPPart, BGVDay10%off, BGMPB2020, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, bgshOOp10, BGRC902, BgoFErTaSchInA10, BgcLuBofErtA10, BGCuponation10, BGDAVIS, BGHONEY2110
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for DALRC ENGINE 40A Pro 3-5S RC ESC is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).