Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (306.35 USD): BGGAL8
Coupon (306.35 USD): BGJON8
Coupon (306.35 USD): tRaDetRaCKeR
Coupon (306.35 USD): 8wEbgaInS5
Coupon (306.35 USD): pROMo8cuPoN
(CouponsFromChina.com tip: just apply this code in your 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): BG8cb8c3, Drones6, BANGGOODSD, 6GSGIT, BG1e83ef, BGdfee0a, BGRACING1125, CouponsDE, BGfcf8b7, 00c906, BGb1e4e6, CouponsdeFPV, MVC8SPRING, 8BGwbg2204
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for Flywoo CineRace20 HD 2 Inch 4S Drone BNF Polar Nano is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).