Help!!!
Marble Collegiate Church has a Gospel Choir made up of parishioners and it's very good. You might talk to the musical director (It used to be David Brown - not sure if he's still the one) I imagine if you could arrange to hire them you'd need to pay for more than a half hour, to include travel time and since they generally perform for church functions I'm not sure if they even will hire out, but it's worth a call.
