"All of these are qualitative definitions. They make no attempt to define quantitative limits."
Either a law is broken or it is not. What does a 'qualitative' definition mean?
Nobody's talking about laws being broken. At least not civil laws ...
What does a 'qualitative' definition mean?
One that is limited to a description of the NATURE of the item. If I say something is "big," it doesn't mean the same as if I say it is "100 feet high by 90 feet square at the base." The latter is quantitative; it assigns numbers to the object.
In your definitions, you didn't describe "stealing" as "appropriation of property belonging to someone else, said property's value in excess of $1."
"Gouging" is the same kind of offense. It means making inordinate profits by manipulating the market, or by exploiting an inflexible demand. If you were dying of thirst and someone had cornered the market on water so they could charge $50 a glass, they would be gouging you. Would they still be guilty if they charged you $49? How about $20? $10?
The offense isn't quantifiable, but it still exists.
By the way, the offense has nothing to do with your ability or willingness to pay the price demanded. If you were dying of thirst, $50 for a glass of water might seem reasonable, even if usurious.