The 450mm drone frame kit we built is sold by Hawk’s Work based in the UK, but ordering from the UK may take longer than buying it on Amazon here.  It costs around $400 in kit form and includes the flight controller.  There are a series of videos we watched in the class located here. The autopilot (flight controller) we used is a standard off-the-shelf Pixhawk 2.4.8, and we used the Ardupilot software, with Mission Planner as the configuration and flight planning tools.  If you want to be interactive with the drone, then you may want to download and install the mission planning software and install it.