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 (7.19 USD): BGdragonBoat
(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): BGRM20, BG08028M, AFfbG10, BG12MRP, BGCITYADS2019, BGGEPPart, bGhOnEy10
(probably won’t work, but you can try them out)
Price history and price alert
Check out price history chart (for all/most countries) for Racerstar MAMBA 08028 12000KV 2S 16000KV 1S RC Motor.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).