What it means
You say this when something's so stupidly expensive it feels like cash isn't enough and they're asking for spare body parts too. It's a big dramatic moan for prices that punch your wallet in the throat, whether it's rent, tickets, repairs or some tiny thing with a wildly rude price tag.
Usage examples
"Parking in the city centre costs an arm and a leg these days."
"A decent flat in the city centre costs an arm and a leg these days."
"Getting the roof fixed cost an arm and a leg, there goes the holiday fund."
"I'd love to go, but those festival tickets cost an arm and a leg."
"We looked at one tiny sofa and nearly laughed, it cost an arm and a leg for no reason."
Where it comes from
The likeliest tale is grim humour from after the World Wars, when so many had literally lost limbs that "an arm and a leg" became shorthand for the steepest price imaginable. Something that costs an arm and a leg is wildly, wince-inducingly expensive.
Other ways to say it
This expression also appears in
