gigacity_amn via Amazon offers Prime members the Gmyle 4.8-amp Dual USB Compact Car Charger in Black, model no. NPL720018, or White, model no. NPL720020, for $6.98 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $6.74.) That's the lowest total price we could find by $4. It features two 2.4-amp ports for simultaneously charging two devices.