Highly expensive. Too, too costly. Imagine something so pricey you would have to give up your body parts to pay for it. One theory on the origin of this phrase is that 2 centuries ago when painting a portrait an artist would charge for each arm or leg to paint as they were more difficult, thusly many portraits were simply a face and torso and someone behind a desk.
“I was going to get an electric car until I discovered that they cost an arm and a leg.”