All of Arkham Horror LCG will ultimately be available in market clearing quantities. Clearly, FFG did not anticipate the game's popularity (which is a good thing that it's so good). They have a track record of getting back on track at the speed limit of their supply pipeline. How long that will be is not clear (to me, anyway). But it'll work itself out, I'd bet, in the next six months. This has happened many times, X-Wing and (currently, Star Wars Destiny) as examples.
Thanks for the info! More of a reply than I expected to get!