Newegg has the Kill A Watt P4400 Electricity Usage Monitor on sale today.
I have one of these Kill A Watt’s and use it to determine how much electricity each of my HTPC and other gadgets are using. It’s cheap and worth every penny. This helped push me towards weaning myself off of full-blown HTPC’s at the TV and use more efficient extenders instead.
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Kill A WATT P4400 Meter/Monitor$15.14 (17 less $3 coupon plus $1.14 tax) Use Coupon Code= EMCYWZP45
This same device cost $19 at Amazon