Leviticus 27:8

And if the man be too poor for the valuation, he shall stand before the priest; and the priest shall value him: according to what the man who has vowed can afford, the priest shall value him.

But if he be poorer than thy estimation, then he shall present himself before the priest, and the priest shall value him; according to his ability that vowed shall the priest value him.

But if he is poorer than your valuation, then he shall be set before the priest, and the priest shall assign a value to him. The priest shall assign a value according to his ability to pay.