Altair 8800a on EBAY

Though the "old computer" market has reflected little that resembles any sort of common sense. I can't imagine why you'd believe that an item, the supply of which is finite, and the demand for which seems to have grown steadily since its introduction, in spite of its qualitative aspects, (meaning I think it is, was, and always will be a bit of rubbish, but that's from where I sit) would decrease in the future. Its value hasn't increased, but its price has. That's the way of things collectable. After a certain point, its technical merits are completely irrelevant. Think of it as a big, clunky, indian-head penny. I'd say your guesstimate of a decrease in the future is based more on wishful thinking than on a realistic view of the collectors' probable behavior.