Drone with px4 autopilot including camera

Hey guys,
I would like to use a drone with camera with the px4 autopilot.
Regarding the drone, I would not like to spend a lot of money.
I would prefer an inexpensive fpv drone for example for 300 euros.
The camera doesn’t have to be good either. If you think that it would be easier with for example a Phantom 3 se, I would also like to use that.
Or if you basically know a better / suitable drone that costs under 450 euros, please write it in here.
As far as I know, you have to install a suitable flight controller in the drone.
If you could now use for example a Phantom or fpv drone, how do you install this?
So a description as detailed as possible would be great.
But maybe someone knows a similar project. Then just like to write the link of the project pure.
The camera does not have to work directly with the autopilot but I would later during, for example, the autonomous flight simply like a live view. The remote control can be made in a different way, right?
So it would be best if everything works together, but only if it is realistically feasible.
I am also still a beginner in this area.