You can create price alert here, copy coupons and view price history. Do you want to know what the best price is?
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):
2.4G mode: AFHDS 2A, Failfe: Yes, Band width: 135, Frequency range: 2.408-2.475GHZ, Weight: 0.9 grams, Working current: 20MA, Output signal: PWM, Distance: 400+ meters, Channels: 4CH, Dimensions: 11 * 25MM, Receiver sensitivity: -92DBM, Supply voltage: 3.3-10V
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($15.93): BGGAL8
2. ($15.93): BGRCParts8
apply code in your basket (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): FS2A, 20OFFRSF, Parts8, BGaDmITAd, BGCITYADS2019, 2020CNY, BGVDay10%off, BGFS12, BGFKY11, bGhOnEy10, BGTT10, BGflysky11, BGRCRR9, BG11SHOP, 13f142, BGCuponation10, BGDAVIS, BG70e5fc
(these coupons are old, so probably won’t work)
Price history and price alert
Do you need price history chart (for all/most countries) for FS2A 4CH AFHDS 2A Receiver? There we go.
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)).