Pisen via Amazon offers the Pisen 4-Port Portable USB Wall Charger in Black for $9.99. Coupon code "ADDKH5OW" cuts the price to $6.99. With free shipping for Prime members, that's $1 less than last month's mention, $3 off list, and the lowest price we could find. It features a 100- to 240-volt input. Deal ends January 14.