If you roll up your sleeves a bit you can get them for free. Here is how: Got to Free EDU Blog Finder | How to Get EDU Backlinks | Edu Links Seo and use their tool to find .edu blogs to leave your link. Also make sure to download the Firefox plugin SeoQuake - seo toolbar, plugin, seo extension for Mozilla Firefox. This will let you see which .edu sites have the highest PR in a blink of an eye.
Happy back linking