eBoot Online via Amazon offers the eBoot 22-watt 2-Port USB Car Charger in Black/Red for $12.99. Coupon code "5E33XGHL" cuts it to $8.99. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, it adds $5.07.) That's $14 off list and the lowest total price we could find. It's compatible with most tablets and mobile devices and automatically stops charging when there is danger of overcharging or lower/over voltage.