Unfortunately it's not simple swap and play. I'm not saying it can not be done but it's quite involved. Yes, everything fits the same in place, but Can Bus nav must be properly coded, a gps receiver antenna needs to be purchased and installed, steering wheel with additional buttons that again needs to be installed and can bus coded to the car and some other minor stuff. So much that the guy that wanted to do this here in Serbia gave up. I do have his rather good instructions in Serbian if it will help. 200 eur is a very good price though, I've seen them on Italian and german eBay from 300,350 to 600 eur just for the receiver, and the antenna is anywhere from 30 to 60 eur, steering wheel couple hundred depending on condition. Maybe it will work just swapping it for the nicer screen and MP3 capability without the nav part but you would have to try it.
Finally, I have never been impressed with any factory nav system. The maps are never as good as the latest aftermarket IGO or Garmin stuff. Also having Nav on my phone means it's always with me in any car or pedestrian situation.