eCase via Amazon offers Prime members the KMASHI 31-watt 4-Port USB Charging Station for $9.99 with free shipping. (Non-members can spend $35 to qualify for free shipping; otherwise, shipping adds $4.99.) That's $29 off and the lowest total price we could find. It includes two 5-volt/1-amp USB ports for smartphones and two 5-volt/2.1-amp USB ports for tablets.