ZWave Products via Amazon offers Prime members the Z-Wave Smart Energy Switch for $29.89 with free shipping. (Non-members can spend $35 to qualify for free shipping; otherwise, it adds $6.85.) That's tied with our mention from three weeks ago and the lowest total price we could find by $17. This device allows you to monitor energy consumption and remotely operate power via other Z-Wave devices.
Of note, Z-Wave via Amazon also offers the Z-Wave Smart Energy Switch 2-Pack for $58.99 with free shipping.