A no cost solution if you already have a tablet (I have a Samsung Tab2), is using it as a navigation device. I set my route using Google Maps on my PC, then send the route link to my tablet. When I open the map on my tablet, I get the option to download the map route to the tablet so I can use it offline for GPS navigation.
The screen is way larger than any GPS unit - 10-inches, and I have it mounted in a cup holder mount in the truck. The screen is so large I don't even need to use glasses to read it with my old eyes. The Google maps are far superior to any GPS unit I have ever purchased, and I currently have Garmin, Magellan, and Rand McNally units in addition to the GPS built into the truck, all of which have map errors. Don't get me wrong, Google also has it's faults, but I have never encountered any mapping system that is without error.
I've used it several times on trips over the past year, and now wish I had not wasted the $ on my latest Rand McNally Overdryve 7 RV unit. Just for fun, I currently use the truck GPS, the Rand McNally unit, plus the tablet for navigation, and without exception, the Google maps on the tablet has been the most accurate.