Your best bet is to try to have Playboy Home Video to make copies specifically for the Society. You are a not-for-profit organization and they might produce a special run with the restriction that only the Bix Society is permitted to sell.
I realize that this is easy fo me to say, and that it may be very difficult to procure permission. I don't see any other solution, It is unlikely that Playboy will reissue the DVD commercially through usual channels (amzon, barnes and noble, etc.).