Okay, first and foremost I am crap at DIY! So what I'm proposing
might be a bit of a pipe dream.

I want to build or buy an outdoor table tennis room. It should be
easy for a moving company to disassemble. I also want it to be
waterproof. It doesn't need windows, and lighting and heating could
be provided by portable devices.

It's important that the floor is wooden for best bounce.

The minimum dimensions of the table tennis area are supposed to be 25
feet long by 13 feet wide by 10 feet high, so these would need to be
the internal dimensions of the building.

I would probably place it on my lawn as I have no interest in my
garden.

What do you reckon? Make or buy? I'm really looking for a very
inexpensive solution.

Thanks in anticipation :-)