Arm and a leg
If something costs an arm and a leg, it means that it is outrageously expensive and therefore perhaps too painful or too exorbitant to pay the price asked. It is, of course, a hyperbole or an exaggeration because there are very few things in life that are worth the loss of an arm or a leg, let alone both. In this sense it is similar to expressions like ‘give one’s right arm’ for something. Although when people say, “I’d give an arm and a leg” for something they are actually mixing metaphors, because the expression is most definitely ‘cost an arm and a leg’ and not ‘give an arm and a leg’. A popular and often quoted misconception is that ‘arm and a leg’ derives from the practice of portrait painting, where head and shoulder portraits were cheaper than full-figure portraits with arms and legs. This is nothing more than a popular myth. ‘Cost an arm and a leg’ is in fact American in origin and first appears during the mid-20th century, c.1949. Before this, during the 19th century, there was an earlier American expression that something could ‘cost or take a leg’. The ‘arm’ part was only added about a hundred years later. This may have been connected with the fact that many US veterans returned from World War II as amputees, but this is also unproven. The expression simply remains a figurative and exaggerated way of describing an exorbitant price.