Just a few points to clarify. I will be posting a new article on the retrofit once I've finished off a few loose ends.

Yes it would be applicable to a 07. Prices vary depending on how the car is configured and what features you want enabled. There's also a few paths to the same outcome, and depending on the path you choose, prices vary. $3K is a good ball park price though.

Now, to be clear. BMW do not offer this retrofit. So there's a few things you need to understand.

1) Since BMW don't offer it, you'll need to do the installation yourself, or work with a shop to do it for you.

2) and more importantly, you'll need to work with a vendor that can do the programming aspect for you. In a way, that's the most important bit of the retrofit.

Now a very important bit. Should you're car ever need to be programmed by the dealer due to a necessary software update, the old system will need to be put back in temporarily. That's just the way it is. For regular maintenance, etc you can leave the new system in.

Now, installation is something folks can do themselves. Just makes sure you've got some good tools and you're clear what you need to do. Once its clear .. and you know how things are removed, I believe you can swap the system in and out within 30 minutes.

Again, i will post more info once its all finished up. Hope this helps.