Harman Kardon offers the refurbished Harman Kardon Invoke Bluetooth Speaker with Cortana in Graphite or Silver for $39.99 with free shipping. That's $10 under our December mention of a new unit and tied as the lowest price we've seen. (It's $10 less than the best deal for a new unit today.) It features: 3 woofers 3tweeters 2 passive radiators Cortana voice control frequency response of 60Hz to 20kHz Note: A 1-year Harman Kardon warranty applies.