cost an arm and a leg

slang To be very expensive. A noun or pronoun can be used between "cost" and "a" to indicate the person spending the money. College tuition costs an arm and leg nowadays. I'm sick of paying rent in this town. It's costing me an arm and a leg!

If something costs an arm and a leg, it costs a lot of money. It cost us an arm and a leg to get here. But it has been worth every penny and more. Note: Verbs such as pay, charge and spend are sometimes used instead of cost. Many restaurants were charging an arm and a leg for poor quality food.

Excessively expensive, exorbitant. The first phrase is American in origin and dates from the mid-twentieth century. The source is obvious: giving up an arm and a leg to buy something is clearly too costly. The use of “pretty” to mean considerable in amount was originally British and is now archaic except in a few well-worn phrases like this one, a cliché since the late nineteenth century. It was common throughout the eighteenth century, and crossed the Atlantic as well (“The captain might still make a pretty penny,” Bret Harte, Maruja, 1885). A similar term was a fine penny, now obsolete.