iirc you had to pay something like $5/month after spending $250 for the sensor just to have access to the data! After spending $250 for it, I would have like to be able to write my own script to read the data off the device and not rely on their web service.... not having open access really turned me off...
This one is much cheaper : http://www.amazon.com/Black-Decker-EM100B-Energy-Monitor/dp/... and it occasionally can be had for a simple $25... sure it'd take some hacking to get the data to the computer, but avoids the insulting monthly fee!