Our
theatre's entire budget comes from ticket sales and donations of time and money from PALs, a group run (mostly) by parents of the student performers. The department gets minimal funding from the school, which allows us to have crucial autonomy (we probably wouldn't have been able to do
Sweeney Todd or even
Jesus Christ Superstar if the administration had their way).
I would talk to any groups in your area that support the Arts. Explain to them that you're strapped for cash and in need of lighting equipment. If you have a definite plan for spending the money, they will probably consider a grant.
Also, appeal to the parents of the performers. As a parent, they want their kids to have the best facilities available, and if they see giving you money as a way to manage that, then they'll do it.
Hope this helps...