RE: Too big of prop?
If you are looking for a budget build, you can probably get a big brushed motor from a blender or some other kitchen appliance. Some blenders have monstrous motors inside.
These would be good because they have a hell of a lot of torque. Problem here is that they run on 120 volts.
No problem, if you can get some copper wiring you can easily rewind a brushed motor for more rpms and you will have yourself a more powerful motor, all be it less efficient.
You can probably find some old kitchen appliances in a dump or something. not too sure.
But it would probably be easier to go with a massive brushed motor instead of brushless.
The controllers are also a lot less expensive.
Heck, you could also get those super strong neodymium magnets and stick those to the sides of your brushed motor, it's a real quick fix to get more power from brushed motors.
Also with a brushed setup you would need a big prop because you aren't getting the same rpms, but with enough torque you could swing a mighty big prop.
Hope this is helpful.
Clock.