Matek F405-STD RC Flight Controller (Banggood, Aliexpress: Size: 36x36mm, Weight: 7g, IMU: 32K ICM20602 gyro/accelerometer (SPI), Mounting hole: 30.5mm, MCU: 168MHz STM32F405RGT6, OSD: BetaFlight OSD w/ AT7456E chip, Baro: BMP280 (I2C) (the best price with coupon)).
You can create price alert here, copy coupons and view price history. Let’s see what best price is ATM.
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($52.89): BGJON8
2. ($52.89): BGRCParts8
3. ($52.89): MVC8SPRING
paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): osdmin, TTxBG10, aff7off, BGMF405, AFfbG10, BGF405, BGSTD, BG12MRP, BGWKF405, BGF405STD, 0e7f33, BGST66D, BGAFF10OFF, bGhOnEy10, BGSTDFC12, BGMT405, BGdragonBoat, BGSS10%SW, bgshOOp10, BgoFErTaSchInA10, BgcLuBofErtA10, BGF405CM, BGCuponation10, BGDAVIS, BGHONEY2110, 13f142, Parts8, BG44606e, 00c906, BG1efeb0
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Other warehouses/versions
This item is available in 1 another warehouse/version!
1. Europe – Matek F405-STD RC Flight Controller [EU/UK] ($-3)
Price history and price alert
Here is price history (for all/most countries) for Matek F405-STD RC Flight Controller. The lowest price was: $19.99.
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)).