P3 P4400 Kill A Watt Electricity Usage Monitor for $17.59 after code 0118EL20P.  Here is a screenshot for your reference.  Shipping is $4.99 for a total of 22.58 shipped or free on orders over $25.  Kill-A-Watt helps identify power-hungry devices by measuring their actual usage.  Here is a review and a video clip about what this device can do.  Alternatively, it is currently available at Amazon for $20.37 with free shipping on orders over $25.