an arm and a leg

In George Washington’s days, one’s image was either sculpted or painted. Some paintings of George Washington have him standing behind a desk with one arm behind his back, while others showed both legs and both arms. Prices charged by painters were based not on how many people were to be painted, but by how many limbs were to be painted. Arms and legs are limbs; therefore, painting them would cost the buyer more. Hence the expression, “Fine, but it’ll cost you an arm and a leg.” Artists know hands and arms are more difficult to paint. At the Academy of Art University (SF), there is a stand-alone class for hands and heads.