Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. We have found one coupon for this product!
Link: Banggood product page
Coupon (103.32 USD): BGGAL8
(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): BGFTI8, Parts8, BGCITYADS2019, Email5, BGFLYT8, BGVDay10%off, BGFLYIT, bGhOnEy10, BGSS10%SW, bgshOOp10, BGRC902, 7d18f7, BGRCRR9, BGCuponation10, BGDAVIS, BGRRCB10, BGradio9, BG70e5fc
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for FsFly T-i8 RC Transmitter is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).