Leviticus 27:1-10

The Lord spoke to Moses: “Speak to the Israelites and tell them: When someone makes a special vow  to the Lord that involves the assessment of people, if the assessment concerns a male from twenty to sixty years old, your assessment is fifty silver shekels  measured by the standard sanctuary shekel.  If the person is a female, your assessment is thirty shekels.  If the person is from five to twenty years old, your assessment for a male is twenty shekels  and for a female ten shekels. If the person is from one month to five years old, your assessment for a male is five silver shekels,  and for a female your assessment is three shekels of silver. If the person is sixty years or more, your assessment is fifteen shekels for a male and ten shekels for a female. But if one is too poor to pay the assessment, he is to present the person before the priest and the priest will set a value for him. The priest will set a value for him according to what the one making the vow can afford. “If the vow involves one of the animals that may be brought as an offering to the Lord, any of these he gives to the Lord will be holy. He may not replace it or make a substitution for it, either good for bad, or bad for good.  But if he does substitute one animal for another, both that animal and its substitute will be holy.