There are many offline Android GPS apps. Here are some of the better ones:
* Seem to be the highest rated, but YMMV.
You can also download Google Maps for any area and use them offline, but you won't get vocal navigation or online directions, just GPS-sync'ed maps, like a paper map.
Many of these apps are FREE, and some are very inexpensive. No need to spend a lot of money.
The OSM Project (open street map) provides free maps that are used on a wide range of Android apps (openstreetmap dot org)
Before you commit to any app, always download a demo and use it for a few days.