When it rains it pours! Funny how things work. When I bought the one in the collection 3-4 years ago I had never seen one before in any reference or in any collection. One was listed a few weeks ago and now this third one has surfaced. The set that ended recently sold for a reasonable $838 but the enclosure was in arguably lesser condition.
09/18 Update: This sold for $809.99. The sustainable value tracks closely with guide value of $775 for both items - the Bogie Book itself and the exceedingly rare enclosure.