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I'm assuming you're referring to: https://itunes.apple.com/us/app/navigon-europe/id320279293

As @old-wiz said, that's $79.99 USD so I doubt you'll be able to get it for free. If you're looking for free alternatives to Navigon, there's: Google Maps, Apple Maps, and Waze that I am aware of.

If you use Apple Maps, keep in mind that not all features will work in every country, here's a list: http://www.apple.com/ios/feature-availability/

If you're trying to have navigation without data then of the free options I think Google allows you to download maps for offline use as per: https://support.google.com/maps/answer/6291838?co=GENIE.Platform=iOS&hl=en
 
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