OutletMP3 via eBay offers the open-box Logitech Bluetooth Speaker Adapter, model no. 980-000910, for $22.48 with free shipping. That's tied with our March mention of a factory-sealed unit and $4 under the lowest total price we could find for a factory-sealed one now. It features push-button pairing, multi-point connectivity, and a 3.5mm jack.
Note that this item is new but comes in a non-retail package.