How Many Tickets Can I Buy?
You can buy as many tickets as you want! Some Broadway shows set limits at 8 tickets per person, but you can usually go back online (or call back) to get more tickets if you need them. If you need over 20 tickets you can get a group rate, but its not usually cheaper, but it does allow you to get the tickets now and pay for them later.
Broadway Insiders Tip:
Is an amateur mistake to buy eight tickets in the same row. It is like going dinner with eight people, where you never end up talking with the people at the other end of the table because they are so far away. It is much better to buy Broadway tickets four at a time, each set sat behind the other. This works so much better than eight in row and gives everyone better views, because you can ask people in your group to move if a tall person is blocking someone.