Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is no active coupon in my database right now (for 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): BGFrSkyR9, aff7off, BGR9MI, 502C6B, BGR9NNY, FBCOUPON1
(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 FrSky R9 Mini 4/16CH 900MHz RC Receiver.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).