A real minister/officiant does NOT charge to perform the ceremony. It's a tradition for the groom to "sneak" a tip to him, by slipping a folded bill into his suit pocket when shaking hands, or a "thank you" card, or during the reception, the Ring Bearer hands the money to the officiant during the reception dinner. Or, think of your own fun, whimsical way to thank them. I was a best man in a wedding once, and I tipped the officiant with a $50 bill rolled up in an airline bottle of Jack.

For a professional officiant or celebrant, somewhere between $400-1000 is appropriate depending on travel and if they have to hike out to your ceremony spot with you!