I doubt you'll find something like that, at least for free. I've never seen a paid template either (although that makes me think I should create one since it's within my area of expertise lol). You can get a good idea by looking at examples from other companies. If you're looking mostly for design ideas that would be a good bet. If you're looking for what specific information it should contain, you can take a look at my site at www.jhmattern.com - if you go to the online press rooms page, there are a few lists of content (press rooms would include the same info as media kits), just to give you a breakdown of some of the things to include when you create yours.