There is a world in difference in cost of NavBox Pro & FlyMap. They aren't really compeditors. FlyMap is way more expensive because it is a GPS solution as well as flight planning.
If you are considering a full flight planning & GPS system, then you should give PocketFMS a look. Perfect for VFR, but doesn't do airways. You can get a 30 day free trial at
www.pocketfms.com dp