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]
(..) Look, I'm doing this with you right here. Fine, fine. Oh! I'm Henry Morgenthau, owner of delicious and expensive hams. Don't I know you from the grocery store? Kill! And scene. (Jake) (..)2013 TvShow: Brooklyn Nine-Nine Title: Pilot Season: 1 Episode 1
(..) - Yep. - What about this fancy ham stuff? - Jamon Iberico. - Yes. The perp left a really expensive TV but then stole ham? It doesn't make sense. Is there a place nearby the crime scene that sells it? - Beneficio's might. (..)2013 TvShow: Brooklyn Nine-Nine Title: Pilot Season: 1 Episode 1