Gleckel filed a civil action and subpoenaed Cunningham$$s financial records, including last year$$s bank statements. The beginning bank balance January $1$ was $$3,463$ and the ending bank balance December $31$ was $$2,050.$ Over the intervening $12$ months, Cunningham$$s per month gross salary was $$3,600$ with a net of $$2,950.$ His house payments were $$1,377$ per month. In addition, he paid $$2,361$ per month on a new Mercedes $500$ SEL and a total of $$9,444$ last year toward a new Nissan Maxima $($including $$5,000$ down payment$).$ He also purchased new state$-$of$-$the$-$art audio and video equipment for $$18,763$ with no down payment and made total payments of $$5,532$ on the equipment last year. A reasonable estimate of his household expenses during the period is $$900$ per month $($$$400$ for food, $$200$ for utilities, and $$300$ for other items$).$

Required:

Using expenditure analysis, calculate the amount of income, if any, from "unknown sources".