They are on sale (and being sold) in Germany at the Music Store. And since a few weeks in The Netherlands as well (Bax Shop).
Music Store has them in stock. Bax has an estimated delivery time of 4 days, although I doubt very much if that is true.
Note that Studio Logic initially produced only a very limited amount of units to see where it would go. If it sold well, they would take it in another production run. If not....well... they ditch it , don't know...?
Since then I have no idea how well they are selling, but considering the Numa Concert is € 1499 incl TAX in homeland Italy , but € 1729 in other countries, I doubt if there's much interest outside Italy. An indication may be that I haven't seen any recent reviews or tests either and no user reports whatsoever. Since the introduction and first YouTube movies and some Messe reports, things look as if they came to a stand-still with the "concert". Happens more often with StudioLogic - not the most communicative company in the world I'm afraid.
For € 1499 and ready to try at a local shop I'd certainly check it out. But I wouldn't take the risk of ordering it unseen / un tested.