Not necessarily. I'd happily do it for a reasonable hourly rate + transportation. It would end up costing not more than a few thousand dollars, which is very reasonable given our legal system.

Hell, if it seemed outrageous enough I'd probably do it for transportation costs alone.

I'm sure I'm not the only one with this outlook.

It might not be as much as you think. I know professionals who’ve been paid a few hundred dollars to be an expert witness more than once, but usually in medicine. It’s easy money for someone if a lawyer often does certain cases that require an expert witness.