In Case You Missed it
Whether portable handheld or panel-mounted, GPSes are the wave of the future in avionics, and these units can store and display a remarkable amount of detailed information. With nifty docks, handhelds can perform much like the panel-mounts in the cockpit, yet be removed for use in other vehicles.
PS Engineering and Garmin have kit-focused audio systems for under $2000. They have generous feature sets and high-end audio quality.