See if there are any businesses or churches or such in the area that will sponsor your show costumes or a part of the costumes. A couple of years ago, we did a musical, from a different publisher ;) ;) and the local Catholic church sponsored all of our nuns. They provided the habits, and even purchased wooden crosses for 12 nuns (of course, it helps that the priest is a real theatre fan {he also tutored all of them in the Latin that they had to sing}). Then last year when we did "Fiddler on the Roof", we were able to approach a Jewish synagogue, and they shared with us some of their prayer shawls, and a lot of their expertise. It also has really helped to build community involvement.