Most major suppliers will have an educational division. The trick is trying to get past the salesman and get to the PR guys for donations. Are you teaching the class through a community based outreach program or non-profit entity? Do you guys have a PR director or advancement person that might have some corporate contacts? How about friends who have family members who work in banks, etc? Ask them to check with their PR departments to see if they donate to worthy causes.

You could always contact places like B&H with a letter on official stationary detailing your plight and asking for a corporate donation, just run it through your people first to make sure they can furnish a letter thanking the donors, so they can use it as a tax write off.

Good luck with it.