I found an older Magellan Maestro 3100 at a garage sale for $5.00 came with car adapter and a good battery with a sturdy OE windshield mount. Works well, lets me view where I'm going, has POI's, can perform routing, etc.
If cost is a factor take a look on eBay or other site. There's plenty of used gps units (Magellan and others) with ~3 to ~7 inch screens.
Another option might be a unit like this one with gps maps and navigation. I don't really know anything about them other than see them for sale online.
For around $150.00 you can get a gps navigation unit with map and 7" touch screen along with all the other features such as WiFi, Bluetooth, DVD connect, connect to rear view camera, connect to Android 5.1, etc.
http://www.ebay.com/itm/7-Touch-Screen-For-Android-5-1-Car-DVD-Wifi-GPS-Navigation-Dual-Core-Lot-LO-/162660174644?var=&hash=item25df4d4b34:m:mTEyjuPknRlWgWPIaT3_QTA
Under $50.00 http://www.ebay.com/itm/KKMOON-7-HD-Touch-Screen-Car-Portable-GPS-Navigator-Navigation-Free-Map-US-X3N8-/272362830051?epid=1882896250&hash=item3f6a16f8e3:g:emUAAOSwvzRXyjKc
http://www.ebay.com/itm/Portable-7-HD-Touchscreen-Car-GPS-Navigator-Navigation-FM-USB-TF-MP4-Video-Play-/141923317592?hash=item210b49f758:g:9h8AAOSw3gJZH7qG
