Our CASM is 9.73 cents per available seat mile. MSY to BOS is 1,448 statute miles, according to FlightAware.
So, it costs us (.0973 * 1,448) $140.89 to fly one seat from MSY to BOS. We plan an average passenger weight of 195, IIRC. So, to fly a 200 pound person from New Orleans to Boston costs us $141.