As of December 2015, one of the best-selling GPS navigation units for vehicles on Amazon.com is the Garmin Nuvi 55LM GPS Navigator System for about $90. Best Buy also has a selection of affordable GPS systems such as the TomTom VIA 1515M 5-inch GPS, which costs about $100.
Amazon reviewers give an average rating of four stars to the Garmin Nuvi 42LM 4.3-inch Portable Vehicle GPS, available for about $90. The Garmin Nuvi 55LM GPS Navigator System is both less expensive and better reviewed than the 42LM model, receiving an average rating of 4.5 stars from Amazon.com users. Walmart offers the TomTom VIA 1510M SE 5-inch GPS Unit for $100.