You didn't just ask for a definition. You asked for a
quantifiable definition. I can provide the qualitative definition; Webster's already has. But I can't put a number on it, any more than you can put a number on "stealing" or "cheating."
Which doesn't mean that those offenses don't exist, or that they can't be egregious.
"But I can't put a number on it, any more than you can put a number on "stealing" or "cheating.""
Stealing is defined as the taking of property without consent of the owner. Cheating is appropriation of something by subterfuge.
Price gouging, in general is charging an exorbitant price by taking advantage of or creating a monopolistic market.