You first need to check to see if they are in working order. Is there other equipment in the spare room that could drive these speakers? If not get a hold of a friend with a receiver. Hook the receiver up to the speaker terminals first and then plug the 2+2s into an outlet. Pick out an FM station and make sure they will play cleanly without distortion. When your done, unplug the speakers from the outlet while they are being driven by the receiver to discharge them more quickly.
Advertise them as Acoustat 2+2s with MK-121-2A transformers (non-medallion). If they are in working order you should be able to get between $500 and $700 for them depending on condition, though it very likely will take a while. The pool of prospective buyers for these speakers is small, especially given their size. But don't take my word for it. Post a question on the "Acoustat Speakers" forum. You should be able to get a response from MrAcoustat who is the authoritative source of information for all things Acoustat on these forums.