TechMatte via Amazon offers Prime members its TechMatte Dual-Port USB Car Charger in White or Black for $7.95. Coupon code "GI8MKB7G" cuts it to $4.95. With free shipping, that's the lowest total price we could find by $3. (Non-members can spend $35 to qualify for free shipping; otherwise it adds $6.07.) It features one 1-amp USB port suitable for most smartphones and one 2.1-amp USB port used for larger devices such as tablets.