I can only conclude he is beloved and never put up for sale

I've heard before from used booksellers (an uncle, for one) about certain authors being hard to find/not being sold often. The Beats, graphics novels, etc., are all ones I'd expect. P.G. Wodehouse, when I went looking one day, was equally difficult to find. But Forster? Color me surprised. I would have thought he was enough of a "Classic" at this point that the shelves would have been groaning with him. Hmm.