Alpine IVA-D105 is good for iPod, reliable, built in Dolby processor, and no separate brain to install.
Alpine IVA-D310 is discontinued, ipod contol is sluggish and requires an add on module, has a brain, bigger screen, more onscreen controls than D105. Great unit.
Kenwood 719 has larger screen than D105, separate brain, better ipod control including on screen album art and video control.
Lesser brands like Jensen triple suck and barely function. Yes, they are only $300. If that is all someone has, they need to be buying a regular CD player IMO.