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What you need, is a device that has the South America lifetime maps. As Costa Rica is included in Garmin's South America maps.
You can purchase the lifetime update version at this link https://buy.garmin.com/en-US/US/maps/map-updates/numaps-lifetime/numaps-lifetime-south-america/prod98711.html
With the lifetime update version. Its a one time fee. It can only be registered to one device. But once registered, that device will never have to pay for updates to the South America Maps.
It costs around 90$.. For that reason, you may be better served to buy a cheaper garmin that does not come with lifetime maps, such as this newer model http://amzn.to/1TH8vhI
That way you arent paying the extra fee for lifetime maps for North America, which it sounds like you dont need.
If you have further questions or concerns, let me know.
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