If you have an iOS or Android smartphone, have you considered instead paying for a whole unit, just get a navigation app?

For example I have the TomTom apps and they work great. I get regular map updates and support for new features. The TomTom apps have lane guidance and their GPS accuracy is usually a little better than a standalone unit's I think due to the fact that cell phones have WiFi, cellular towers, and GPS for a faster and more precise triangulation.