GEPRC Triple Feed Patch-1 5.8G 9.4dBi FPV Antenna (Banggood, Aliexpress: Triple Feed Patch-1 5.8G 9.4dBi FPV RX Antenna For LHCP RHCP SMA RC Drone (the best price with coupon)).
You can create price alert here, copy coupons and view price history. What is the 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.
Link: Banggood product page
1. ($17.98): BGGAL8
2. ($17.98): BGJON8
3. ($17.98): BGRCParts8
paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/feV
Old coupons (from the oldest to the newest): Parts8
(probably won’t work, but you can try them out)
Price history and price alert
Check out price history chart (for all/most countries) for GEPRC Triple Feed Patch-1 5.8G 9.4dBi FPV Antenna. The lowest price was: $15.63.
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)).