Her decision to leave the company proved to be an 'expensive' mistake. [=a mistake that caused her to lose a lot of money]
They live in an 'expensive' neighborhood. [=a neighborhood in which houses, apartments, etc., cost a lot to buy or rent]
an 'expensive' shop [=a shop that sells expensive things]
(..) in her bathroom. I have two doctorates, I still had to go in the sink. Oh, my God, and do you have any idea how expensive having a kid is? I read that in Los Angeles, raising a child through college can cost over a million dollars. A million dollars? God, it's like my nuts (..)2016 TvShow: The Big Bang Theory Title: The Positive Negative Reaction Season: 9 Episode 16