Newegg.com has P3 Kill A Watt Electricity load meter and monitors for $14.99 – we use these for the Tweet-a-watt kit, so if you’re looking to get a good deal $14.99 is really good!

Tweet-a-Watt is a DIY wireless power monitoring system. The project uses an ‘off the shelf’ power monitor called the Kill-a-Watt and adds wireless reporting. Each  plug transmits the power usage at that outlet to a central computer receiver. The receiver can then log, graph and report the data. This pack contains nearly everything* necessary to build a single outlet monitor and receiver. To monitor additional outlets, you will need an add-on transmitter pack. One outlet can monitor up to 1500 Watts.

The starter pack contains:

• 2  XBee modules (one for receiver, one for transmitter)
• 2  XBee adapter kits (ditto)
• 1  USB FTDI cable (for updating, configuring and receiving data from XBee)
• 1  bag of parts including 10,000uF capacitor, 220uF capacitor, 2 1% 10K resistors, 2 1% 4.7K resistors, 5mm green LED, 6″ rainbow ribbon cable, and 2 pieces of 1/8″ and 1/16″ heatshrink