Just check coupons out (with price alert and history). Best price?
Output Format Compatible S.BUS, Mode (optional) Self Centering Throttle, FCC, Weight 410g, Certification CE0678, Frequency 2.4055 – 2.475GHz, Low-Voltage Alarm <4.2V, Color (optional) Black, Input Voltage 4.2V-6.0V, Antenna Length 26mm (dual antenna), Dimension 179*81*161mm, Mode 2 (left throttle hand), Modulation System GFSK, Band Number 140, Band Width 500KHz, Transmitting Power <20dbm, Channel 10, 2.4G Mode AFHDS 2A, white, Joystick Resolution 4096 class, Receiver Sensitivity -----, Charging Port Yes (USB)
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($60.47): bGhOnEy10
2. ($62.19): 7d18f7
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 and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGFSI6S54, BGaDmITAd, BGFSI6SCD, 502C6B, BGBFAFF2019, BGCITYADS2019
(there’s a little possibility that old coupon will work)
Price history and price alert
Check out price history chart (for all/most countries) for Flysky i6S FS-i6S RC Transmitter With FS-iA6B.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).