Hi vinrock027, welcome to our community! Congratulations on the great success of your non-profit! Can you please let us know what methods you have tried already to secure a van (or a grant for one) for your students? With your great success rate, you might definitely consider approaching businesses in your area, or even perhaps one of your college graduates current place of employment.
In general, donations of property by businesses can be deducted as charitable contributions at fair market value for qualified non-profits. The closer it gets to the end of the year, the more an area business might be interested in donating a used van for your school.
I look forward to hearing more about your non-profit, and the fundraising campaigns that you already have in place. The more we know, the more our members can help provide some great advice for you.