TDF National Membership (for those outside of NYC) is only $12 a year. If there are two shows you want to see on that date that are available on TDF, you would easily save that much money on the tickets, which are in the range of $35-45 for Broadway shows. I think you probably have to already be a member to see what's on offer for a particular date, but if you ask here, I'd be glad to check for you. Note that a lot of shows send tickets to TDF closer to the date of the show, so additional shows will pop up between now and then (and of course some will disappear as tickets are sold).
TDF is only available for people in one of these groups:
full-time students (high school or above)
full-time teachers
recent graduates (26 years of age and under)
union members
retirees (no longer working and at least 62 years of age or older)
civil service employees
staff members of not-for-profit organizations
non-exempt employees
performing arts professionals
members of the armed forces or clergy
For information on the National Membership, click the link below.
TDF National Membership