BuyDig offers the Aeon Labs Z-Wave Home Energy Meter, model no. DSB09104, for $26.99. Coupon code "AZWSMART" cuts it to $16.99. With free shipping, that's a buck under our February mention and the lowest total price we've seen. (It's a current low by $13.) It can wirelessly report immediate wattage and kWh usage.

Of note, you can also 2-Pack for $32 with free shipping via the same coupon.