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 (15.93 USD): BGJON8
Coupon (15.93 USD): BGRCParts8
Coupon (15.93 USD): BG8RCToy
(CouponsFromChina.com tip: put item in your cart and apply coupon code there 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): 15SE0603, 502C6B, TTxBG10, AFfbG10, BGVDay10%off, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, BGRC902, BgoFErTaSchInA10, Parts8, BgcLuBofErtA10, BGCuponation10, 13f142, BGHONEY2110, BGDAVIS, Tabby20, BG1efeb0, 8Couponsde, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for Happymodel SE0603 1S 19000KV RC 1mm Brushless Motor.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).