No, you can't use it that way.. YOu will hear it in this context, "He made a killing in the market." This means that he made a LOT of money in the stock market. You can use it for other 'markets' as well (real estate market, for example) "Because of the hot (real estate) market, they made a killing on their house" -- you can say this when people sell their home for a huge profit. Often, it means make a lot of money in a SHORT amount of time, without a lot of effort Otherwise, for a particular item, you can say, "The (item) was a steal" meaning "I got it so cheap, it was almost as if it were free

The phrase "a killing" is never used on its own to mean "a big profit" - it is always used with "make", so you could say: I made a killing If I find a buyer, I can make a killing I thought I would make a killing but no-one was interested I'm going to make a killing We might make a killing I'm making a killing by selling these stolen cars I have no idea how the phrase "make a killing" came to mean "make a big profit" - it's just one of those strange phrases... With your example phrase, you could say: I made a killing when I sold that van Hope this helps