If you're a student, or just someone likes to test your luck for a bargain, consider Rush and Standing Room Only Tickets
. Tickets are generally $25-40 and are distributed on the same-day as the show (most often first-come, first-served when the box office opens or by a lottery closer to show-time). Although standing through a whole show might not be appealing, often you can get a seat for the second act if you get a standing room only ticket (which are only available for sold-out performances at select shows).
More: Discount Tickets at the TKTS Booth
More: Discount Broadway Tickets 101