Only one supplement is out of print - Battlegroup Kursk.
Battlegroup Overlord goes back for its reprint this month.
Those are the only two that have been out of print.
Battlegroup Tobruk, Wacht am Rhein, Blitzkrieg, Barbarossa and Fall of the Reich aré all still in print as is the new core rulebook with Normandy lists inside.
So not quite 'half out of print'... Indeed in a couple of months will be only one...
...and Kursk is due to reprint next year.