Best Buy offers the Logitech Wireless Bluetooth Speaker Adapter for $9.99. Choose in-store pickup to dodge the $5.49 shipping fee. That's $10 under our mention of an open-box unit from three weeks ago, the best deal for a new one today by $8, and the lowest price we've seen in any condition. It features push button pairing, multi-point connectivity, and a 3.5mm jack.
It has very good reviews on over 2,500 verified purchases at Amazon; common complaints are poor range and an annoying disconnection process.