TKTS sells tickets to Broadway and off-Broadway shows at a 25–50% discount. Tickets are only available on the same day as the performance, and can't be reserved. At the downtown location, Wednesday matinee tickets are available on Tuesday only, Saturday matinee tickets are available on Friday, and Sunday matinee and evening tickets are sold on Saturday. Payment is by cash or traveler’s check only. TKTS doesn't accept credit cards.
You can get tickets from ticketmaster.com but they're usually at door prices.
If you can get to a library, they have decent discount coupons for all seats. It doesn't matter where you sit, you can see the show from any seat you're in! about 8 years ago