A common misconception is there is no or little support for music education and the arts. The support is out there, you just need to ask around until you find it.
Many businesses have funding allocated for community support, and more specifically education.
Put a special thanks inside the CD jacket thanking the businesses for helping make the CD-recording project possible. Put a special thanks in the school newsletter and school newspaper. These means are a great incentive for the businesses to sponsor your project as they gain advertising exposure and can quickly become known throughout the community as supporters of music educator and the arts. Financial support is not the only way a business can help - Contact local recording studios and ask if they would consider donating or discounting studio time. They may even be willing to record a live performance of your concert on location.