My roommate and I are upstairs.
His dad is downstairs.

The dad likes RC cars and helicopters, that's his big non-summer hobby (fishing, being the summer hobby).

A kit for a car can be over a thousand dollars.
He'll take every piece, and fabricate an aluminum chassis in the place of the heavier and weaker plastic one.
Rather than use the tires that come with the car, he'll make his own with a lathe.
He's got a lot of tools and the like, in the porch.

Still, an engine can be a few hundred.
And there are a ton of parts which cannot be made/fabricated with the equipment he has.
So he spends another thousand a month, on parts for whatever cars he is racing.

It is neat seeing an electric car, an inch wide and two inches long race along at 90mph.



Helicopters are a similar story, except almost every part requires a purchased replacement.
A minor crash might be $1-200, and a major crash could total the helicopter quite easily.

Not a cheap hobby...