Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. There is one coupon available! Pretty cool, huh?
Link: Banggood product page
Coupon (216.76 USD): Parts8
(CouponsFromChina.com tip: apply it 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): BGCuponation10, BGDAVIS, BGradio9
(probably won’t work, but you can try them out)
Price history and price alert
Price history (for all/most countries) for DJI FPV Remote Controller 2 RC Transmitter is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).