My dad recently got an iphone and asked me about getting a cheap usb car charger, like the kind Target sells for $5. And I realized i really don't know anything about them, so I figured I'd ask for opinions here. What are your opinions on cheap ($5 target) usb car chargers/adapters vs the more expensive ones in the $15-$20-+ range? I mean, I'd think there's a difference somehow to justify the more expensive ones (though i see Belkin ranges on amazon from 10-30,...is the $10 a $5 adapter with a $5 brand name? Anyone have thoughts, studies, comparisons, articles, other info that can help me?