worth a king's ransom

"It's worth a king's ransom, this bottle. It cost me two large blue-white diamonds, a mechanical bluebird which sang, and a dragon's scale."

Everyone had been busy burning and burying a creature worth a king’s ransom.

The hoard of almost 500 pieces was a 17th-century goldsmith's stock – worth a king's ransom then and priceless now.

A bushel of March dust is worth a king's ransom.

A time might come when it would be worth a king’s ransom to her.