SmilingMusician,
Instead of going into a studio for recording, @50 Sacred Harp singers were invited to a singing at Liberty Church in Alabama. They sang for a couple of hours in just as they would at an all day singing & it was all recorded. Just the 2 on the soundtrack were used in the movie. The word in FASOLA circles is that there will be a CD released from the rest of the tunes recorded.

Teresa, I clicked your name & see you're in San Francisco Bay area. I hope you've found the Sacred Harp Singers there. I don't know of any in LasVegas.