Just check coupons out (with price alert and history). What is the best price?
Charger port: yes (USB), ANT length: 98.5mm, Low voltage warning: yes(less than 3.5V), Power: 3.7V(800mAh), 2.4G system: AFHDS, Channels: 3 Channels, Bandwidth: 500KHz, DSC port: yes(USB; output: PPM), Weight: 303g, Code type: GFSK, R: 15), RF range: 2.40-2.48GHz, Band: 160, TH range: 45(F: 30, RF power: less than 20DBm, ST range: 90, Size: 151*183*116mm, Model type: car/boat, Senditivity: 1024, Remote range: 100-150m
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. There are no coupons for this product in Banggood.
Link: Banggood product page
Price: $-3
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 and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG44OO99, AFfbG10, BG10UU45, BGRCPART, 502C6B, BGBFAFF2019, BGCITYADS2019, BGVDay10%off, BGFS12, BG10PARTS, BGFKY11, bGhOnEy10, BG464RA, BGAFF10OFF, BG1068QA, BGflysky11, BGdragonBoat, BGSS10%SW, bgshOOp10, BGRC902, BgoFErTaSchInA10, BgcLuBofErtA10, BGCuponation10, BGDAVIS, BGHONEY2110, Parts8, BGRCParts8
(there’s a little possibility that old coupon will work)
Price history and price alert
Here is price history (for all/most countries) for Flysky FS-GT3C RC Transmitter.
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)).