Go down and check coupons out. Remember to check price history if it is available. What is best price?
Plug and Play, SBUS Inversion, LED Driver for WS2812b programmable LED, Built in internal OSD, Fast building using connector system, Full Lipo up to 6s rating, Advanced filtering
Aliexpress
I could not find it on Aliexpress. Click here to search by yourself.
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($43.19): bGhOnEy10
2. ($43.19): BGdragonBoat
3. ($44.15): Parts8
this code has to be applied in your 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): AFfbG10, BGVDay10%off
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Here is price history (for all/most countries) for FlightOne/RaceFlight RevoltOSD/MillivoltOSD F405 2-6S RC Flight Controller.
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)).