Gogo Navigator supports real-time turn by turn navigation throughout the United States and Canada at a decent price. I recently looked at Garmin StreetPilot for iPhone which is currently priced at $34.99. While the app had a great interface and offers turn by turn navigation, I found it had one huge down side. StreetPilot does not store maps natively. This means if you're out of range of a signal you won't be able to access maps since they can't pull from the servers.
Gogo Navigator uses native maps for navigation. Regardless whether you have a signal or not, you can still get turn by turn directions. They offer maps in regular view as well as real-time 3D view. You also have the features you'd expect from a good GPS app like favorites and places of interest (POI). Gogo Navigator is currently priced at $29.99 in the app store which is a great deal for a decent GPS app. It's a much lower price point that most and I found it did the job just as well as some of my other GPS apps. Hit the jump for some screens!