D-Link DWL-P200 Power-Over-Ethernet (PoE) Adapter Kit for $29.99 shipped. Here is a screenshot for your reference.  Alternatively, it is available at ZipZoomFly for $30.99 shipped and available at Amazon for $32.53 shipped.  It transmits power and data over an Ethernet cable up to 328 feet (100 meters) away.  The idea is to eliminate the need to place an Ethernet-enabled device near a power outlet so there is more freedom in the placement of the device.  The power output is adjustable to either 5V or 12-Volt.  More information is available here.  Most places have it for about $38 or more.