Comment low cost - commercial grade (Score 1) 172
checkout the Wattnode.
This device does a lot for the money. There are many different configuration options, and plenty of technical info on their site.
http://www.ccontrolsys.com/products/pulse_output.html
datasheet:
http://www.ccontrolsys.com/downloads/Data_Sheet_WNB_Pulse.pdf
checkout the application notes as well:
http://www.ccontrolsys.com/support/app_notes.html