Check out these sites.
http://www.charitycarauctions.com/ This is where cars go when people donate them. I think there's a $100 fee to sign up for it, but if you can save a couple hundred over what you might pay otherwise, it might be worth it.
Also check out
http://minneapolis.craigslist.org/. There's a cars+trucks section, where you might find a good deal. It's all in the twin cities area too.