Bose dosn't make a subwoofer. They make what they call a bass module (even that is a stretch). Also I believe it is passive so you can't hook to the sub pre out on your receiver. Also the connections are proprietary and will not hook to any equipment except Bose.
While over the top here is a good read
to give you an indication of the level of quality (and respect) that Bose Acoustimass have.