Hi!
You may already have what you needed. But this may help you or someone else: the Theater Development Fund (the folks who run TKTs booth in Times Square) have a second program called TDF. It allows you to buy tickets in advance and for a wider range of shows than the TKTs booth. And no standing in line! The catch is, it isn't open to anyone. But lots of us qualify one way or another. You have to be one of the following:
students, teachers, union members, seniors (62 or over), civil service employees, staff members not-for-profit organizations, performing arts professionals, members of the armed forces and clergy.

You don't (apparently) need to live in NYC, so if you fit one of these categories, sign up. It's $25 a year, but if you're going to buy two or more tickets, it will be a great deal. You can get two tickets advance to the shows on offer. I've seen popular shows in the early part of their runs for $30.

The website gives more details and also tells you what's on offer right now so you have some idea of the range.

http://www.tdf.org