From Garmin:
Question: Why is there a mapping update charge?
Answer:
Garmin® does not compile the map data; we pay royalties on this data and therefore only license it, we do not own it. The routable data is provided by the company NAVTEQ, a respected map data vendor, often regarded as the best in the business.
Last modified on: 07/09/2008
Depending on the device you can purchase a map update subscription. If in doubt call Garmin direct. Depending on the software, device, and subscription there can be a number of answers. Garmin direct will be your best source.
Question: How many devices are covered under the nuMaps Lifetime subscription map update?
Answer:
A nüMaps Lifetime subscription is a map update package that is tied to a single compatible device.
Each nüMaps Lifetime subscription is only for a single user/single Garmin compatible device. One map update package must be purchased for each compatible device that wants to use the nüMaps Lifetime subscription.
Last modified on: 01/16/2009
Get the newest maps available and navigate with confidence with Garmin's nüMaps Guarantee. Simply register your new Garmin nüvi or zumo at my.garmin.com (click here) within 60 days of first using your device, and if there is a new map version available, you'll be able to download it for free! Or if you prefer, you can have a map DVD mailed to you for $10. With the Garmin nuMaps Guarantee, you'll be up-to-date when you hit the road.
Go for the DVD.