We tend to do fair weather boating in familiar places so the £500+ plotter idea was a bit expensive for our needs so we bought a nexus tablet off Ebay, navionics, tilting tablet holder from maplin which is designed to clamp on a music stand, power from 12v socket and an overboard waterproof cover if needed. Total around £130. Can also Bluetooth Spotify tunes and has wifi when needed. Also has a camera and everything else a tablet does but we limit it to music, nav and a few kids games.
Pros are cost advantage, music integration, portability, tilts out of sunlight, easy to review tracks and plan routes anywhere with it, and navionics shows all features we need, including full zoom.
Cons are android navionics not as good as iPad version, can be tricky to pinch zoom when underway at speed, and it does need to be plugged into charge most of the time.
Despite my initial reservations it has never come out the holder, always can read screen and as it is protected by a sloping windscreen it has never got wet. So for us it has been fine and a very convenient solution.