"To cost the earth" means something is very expensive or will require a significant amount of money or resources to obtain or achieve.
Sentences with «to cost the earth»
Chic surroundings which don't cost the earth together with great golf and gourmet dining, are the perfect blend for a wonderful holiday or weekend - break. (greensandgrapes.com)
That whole «long distance relationships will cost you the earth because of your phone bill...» that's mostly a thing of the past. (modernlovelongdistance.com)
This doesn't have to be a weekend thing and it doesn't have to cost the earth at that fancy, newly refurbished spa just down the road! (retailmarketing.com)