what is the name of calpurnia's church and what is the significance of the name?

"First Purchase African M.E. Church was in the Quarters out- side the southern town limits, across the old sawmill tracks. It was an ancient paint-peeled frame building, the only church in Maycomb with a steeple and bell, called First Purchase because it was paid for from the first earnings of freed slaves. Negroes worshipped in it on Sundays and white men gambled in it on weekdays." (Chapter 12)