Correct, and another phrase is: "I would give my right arm to be able to afford those opera tickets!"

"Please help me with an idiom." We use "cost and arm and a leg" to mean something was very expensive. Imagine if you literally had to give your arm, and your leg, to buy it. That's the image we think of when we use this idiom.

lose a lot to get it

Thanks

cost (somebody) an arm and a leg: Means to be very expensive. Example:These opera tickets cost us an arm and a leg!