<< Quite a lot, in the four digit range. >>
If two of those digits are after the decimal point, as in $25.00, fuggetaboutit.
On the other hand, if you're talking about four digits before the decimal, say, $8000.00 then you've got a beef.
May I recommend the collection agency of Smith and Wesson? Or, for instant payback, you may threaten him with my naked mother in law. Trust me, when he regains his vision, and it make take a while, when he can see again you will have your money with interest!!