Just started a small mining operation at home and wanted to get a power monitor to see my total wattage to get a better idea for profitability. I found one sold from a 3rd party amazon vendor for $5.99 with free shipping. The vendor is in china, but expedited shipping was free for a December 1st delivery.
Here is a link [amazon.com]
Also good to see how much your christmas tree, water heater, heat, stove, etc is costing you to keep running.
This can measure current, watts, killowatt hours over time, and more.
I didn't pay any tax in WA