Cheapest flight controller

Hey…i’m building a rover for my university. I need a cheap flight controller under 30$ which can support ArduRover 4.1

Find one on the list of available Rover firmware:
Rover Stable

All this in the link support the latest firmware? This (Autopilot Hardware Options — Copter documentation) why are less?

Also, what is the difference between ArduRover 2.6 and ArduRover 4.1 ? (I have the APM2.6 ArduPilot Mega2.6 Flight Controller that’s why i asking)

Because it’s not as up to date.

100’s of changes and the APM Flight Controller hasn’t been supported for years.