Brand Name: Flysky, Weight: 15g, Input Power: 3.5V-18V, 100% Brand New, RF Receiver Sensitivity: <20dBm(EU), Size: 46*28*22mm, Channels: 4 Channels, 2.4G Mode: AFHDS 3, Color: black, Model type: car/boat, Item Name: FS-GR4 Receiver, Compatible Transmitter: Compatible with FS-NB4+FS-TR4 FS-FG4 Transmitter, Certificate: CE, FCC ID: N4ZFGR400, Modulation: Lora, Frequency: 2.402-2.481 GHZ. Price history, coupons and price alert are available on this page. What is best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
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. I don’t think there is an active coupon right now – at least in my database.
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!
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGFSGR4, 2020CNY, BGVDay10%off, BGFS12, BGFKY11, bGhOnEy10, BGflysky11, BGSS10%SW, bgshOOp10, BGRC902, BGHONEY10, BGRCRR9, BGCuponation10, BGDAVIS, Parts8, BG70e5fc, BGGAL8, BGRCParts8, Tabby20, BG1efeb0, 8Couponsde, MVC8SPRING
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Flysky FS-GR4 AFHDS RC Receiver is here. The lowest price was: $29.99.
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)).