while "the internet" is such a helpful suggestion..
If you have a university near you with a TRULY top notch music program or musical theatre program, then you can check their performing arts/music library. Top music schools always have absolutely grand collections of musical scores; old and new alike. And you could use their copy machines to copy the music for dimes, and you wouldn't have to pay the large amount for the whole book.
And if you don't have a university or conservatory like that around you, then you can always use amazon.com