Check coupons or create price alert down below. You probably want to know what is the best price?
Input Voltage: Support 2-4S Lipo Input, Version: Acro Version / Deluxe Version, Acro Version: Without Barometer and Blackbox, Firmware: betaflight_3.3.0_NOX, Built-in 5V @ 3A BEC, Support Spektrum 1024 /2048, CPU: STM32F411C, SBUS, Built-In Betaflight OSD, Built-in LC Filter, IBUS, Mounting Hole: 20x20mm, Weight: 3.3g, Application: for less than 150mm frame kit, M2.5, and 3.3V Spektrum Satellite receiver, MPU: MPU6000, Size: 27x27mm, support DShot, Proshot ESC, Deluxe Version: With Barometer and Blackbox, Model: F4 Nox4, PPM
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 and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($23.39): BGHONEY2110
2. ($23.91): BGDAVIS
just apply this code in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): AFfbG10, BG12MRP, BGCITYADS2019, BGGEPPart, BGVDay10%off, BGMPB2020, BGAFF10OFF, bGhOnEy10, bgshOOp10, BGRC902, BgcLuBofErtA10, BGCuponation10, xollodrnes37
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – 20x20mm Betaflight F4 Noxe Flight Controller [EU/UK] ($-3)
Price history and price alert
Here is price history (for all/most countries) for 20x20mm Betaflight F4 Noxe 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)).