Price history, coupons and price alert are available on this page. Best price?
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 code price check (UTC time):
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
Banggood
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon 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
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Price history (for all/most countries) for Flysky FS-GT3C RC Transmitter is here.
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)).