I purchased an Alpine CDA-117 strictly for its audio capabilities. It was one of the smartest head units in terms of equalizing, sound clarity, and audio control for my sound system. It has no frills, no navigation & no bluetooth. Alpine also requires the bluetooth and navigation system "Add-On" hardware bullsh!t to use it.
My head unit works in unison with 2 additional amplifiers, a 4 channel and a mono. I have carbon fiber speakers (Kenwood Excelon), all new wiring, braided kevlar Kicker RCA cables, etc. It does it significantly better than my old Pioneer in dash and single din.
My CDA-117 retailed at $350 and was well worth it.
And [MENTION=65101]BrianSD_42[/MENTION] is correct. A $300 Alpine single din head unit can sound identical, if not better than Navi/DVD systems. Most often times a TV headunit will produce less RMS power due to it requiring power to the television and other various components. It comes down to the RMS power output from the head unit to its speakers. A nicer head unit will definitely have its "pros," being that it will have somewhat of an advanced equalizer onboard or sound monitoring system. But comparing Alpines $300 single din headunits to their $1,200 double din, Navi/DVD systems is silly because you are 110% paying for the television and add-ons that a TV would have(Navigation, DVD, etc.), not sound quality.
CLARIFICATION: The above paragraph does not mean that an Alpine TV headunit does not have sound quality. I know one of the Alpine TV head units that cost around $1,000 have some serious EQ settings but I am not a fan of driving and watching TV and my CDA-117 has the exact same EQ system, just not "touch-screened," and less attractive. But, my point would be that, ONLY IN TERMS OF SOUND QUALITY, both would be identical, under factory settings.