I've purchased tickets at BOS on several occasions. It has always taken multiple staffers to figure it out but they finally did it. The counter opens and closes several times during the day based on flight schedules so it's best to arrive at the airport at a time when a flight is near departure. (On one occasion I arrived 30 min prior to a departure and saw a surprising number of frantic passengers cutting it pretty close considering that they needed to check baggage and get a boarding pass.)