Leviticus 27:1-8

The LORD said to Moses, “Give the following instructions to the people of Israel. If anyone makes a special vow to dedicate someone to the LORD by paying the value of that person, here is the scale of values to be used. A man between the ages of twenty and sixty is valued at fifty shekels of silver, as measured by the sanctuary shekel. A woman of that age is valued at thirty shekels of silver. A boy between the ages of five and twenty is valued at twenty shekels of silver; a girl of that age is valued at ten shekels of silver. A boy between the ages of one month and five years is valued at five shekels of silver; a girl of that age is valued at three shekels of silver. A man older than sixty is valued at fifteen shekels of silver; a woman of that age is valued at ten shekels of silver. If you desire to make such a vow but cannot afford to pay the required amount, take the person to the priest. He will determine the amount for you to pay based on what you can afford.