Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. There are no active coupons for this product, but the price is pretty low isn’t it?
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): BGfe8320, BGCL78S, Drones6, BGBat78S, CouponsDE, BGJON8
(there’s a little possibility that old coupon will work)
Price history and price alert
Price history (for all/most countries) for SPCMaker Bat78-S 78mm F4 AIO 20A 2S Drone RTF is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).