Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood.
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BG1714, elec, TS15prime, BGRU8542, BGCITYADS2019, AFfbG10, BG2020NS, BGVDay10%off, bGhOnEy10, BGherra, BgcLuBofErtA10, BG00c906, BGGines
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for DC 6-14.4V RS-550 Motor.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).