I just heard that Berlin Alexanderplatz is out of print! Sheesh. It's always sad when great lit vanishes from bookstore shelves like that. I mean, I know these things are cyclical, and it's only a matter of time before some other publisher realizes no one's putting out an edition, and they lovingly design a handsome new edition of this "lost classic". But still. It's always a bummer.
Of the writers I really adore, there are at least two I can think of off the top of my head that have been almost entirely unavailable for a decade (at least): American pulpster Fredric Brown and Austrian metaphysical mathematician Leo Perutz. I've had a copy of Perutz's The Swedish Cavalier I've been meaning to give away to a friend for years. But I'm petrified that once I give it away I'll never find another copy. It really is a treasure in every sense of the word.
So what are your lost treasures? What is everyone missing out on?