Need Rabbi for interfaith ceremony

Hi there this is not for me,this is for a friend of mine who hasnt joined the boards..
she is getting married this august at a Roman Cathoic church and needs a Rabbi who is wiling to come to the church and perform the ceremony with the preist.The person she has right now wants to charge $850 for being there for 20 minutes( she is not having as mass) Any recomendations are apppreciated. Thanks