[Highland Park] advice needed: local nonprofit looking for vans

Hi neighbors, I'm helping Gwen's Girls, a nonprofit agency that helps at risk girls, acquire a couple of 7 passenger mini-vans.  We would need them to be free or cheap, and in reasonably good condition.  Does anyone have suggestions about where I might look?  I've called some dealerships, and am planning to research auto auctions.   Also if you have a van to donate, please let me know.  The blue book value of your donation will be tax deductible. Thanks! Meg