LifeCycle Events: Marriage and Sexuality: Paying a Matchmaker:
What are the rules about payment of a fee to a shadchon (matchmaker)?
There's an excellent summary of all the laws related to matchmaking,
including payment of fees, in the book Ha-Nisuin Ke-Hilchoson Ch.4; the footnotes there give many references. On the fees see, in particular, Even Ha-Ezer 50, and especially Aruch Ha-Shulchan 50:42 and Pischei Teshuvah 50:16.
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