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]
(..) to sacrificing others... ...in order to protect Queen and country. You know... ...former SAS types with easy smiles and expensive watches. -Rolex? -Omega. Beautiful. Now, having just met you... ...I wouldn't go as far as calling you (..)2006 Casino Royale