Cambond via Amazon offers the Cambond Portable Bluetooth Speaker for $21.99. Coupon code "C7KX2B4Q" cuts it to $19.99. Plus, Prime members receive free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.59.) That's a buck under our August mention, $40 off, and the lowest total price we could find. It features a Bluetooth range of up to 33 feet and built-in microphone.

Update: The price has dropped to $19.99, without the need for a coupon code.