You can create price alert here, copy coupons and view price history. Best price?
Connector: IPEX 4, RF Cable: RG1.13, Cable Length: 85 mm, S.W.R.: <= 1.7, Compatibility: FrSky R9 Mini/ R9 MM Receiver, Frequency: 868/915 MHz, Antenna Gain: 2.0DBi, Width: 168 mm, Weight: 1.3 g, Working Temp: -40~80℃, Impedance: 50 Ω, Polarization: Horizontal polarization, Humidity: 95%~100% RH
Aliexpress
There’re some similar (or not) items on Aliexpress
| Image | Product (link) | Price | Coupons |
|---|---|---|---|
 |
R9MM OTA 868/ 915 MHz IPEX4 T Type Receiver Antenna For FrSky R9M 2019 R9Mini OTA Parts | $3.14 | – |
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. You can get coupon down below.
Link: Banggood product page
1. ($11.67): BGRCParts8
put item in your cart and apply coupon code there 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): Parts8, 2020CNY, BGVDay10%off, bGhOnEy10, BGTT10, BGSS10%SW, BGRCRR9, BGRC902, BG11SHOP, BGDAVIS, 13f142, BGradio9, BG70e5fc
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for T-Type 900MHz RC Receiver Antenna FrSky R9 Mini MM.
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)).