The sages ruled that a woman is bought and married with money. (One who marries a woman using a ring is actually marrying her using the monetary value of the ring). Actual money is not required; any activity which has monetary value is suitable.
For example: If a man who wishes to wed a woman and tells her: “You are sanctified to me through this dance I shall dance before you, in accordance with the laws of Moses and Israel,” and then he dances a dance whose monetary value can be valuated at being at least the equivalent of a perutah (about a shekel), the woman is married.
The Talmudic sages suggest varied and different events which have monetary value.
The sages ask: what is the case if a dog runs after a woman, who flees the dog in fear. A man comes along and tells her: “You are sanctified to me by my saving you from this dog, in accordance with the laws of Moses and Israel.” Is this sanctification valid? What are the issues under debate? On one hand, the woman probably would have been prepared to pay to be saved, so saving her from the dog’s pursuit can be valuated monetarily. On the other hand, since each person is obligated to save others from danger without cost, this saving should not be given a monetary value, and the woman is not sanctified in marriage.. (The Gemara does not resolve this issue, so the woman is subject to doubtful sanctification.)
(Babylonian Talmud, Tractate Kiddushin 8b)