Googling a bit I found an article http://www.nytimes.com/2004/11/28/national/28alpaca.html?pag... implying that the "people are realizing this is a bubble" stage of the bubble stretches as far back as 2004. And one guy quoted in the article says:

When I started, I would tell people I thought the market would be good for another five years. Well, I've been saying that for 15 years

Still, alpacas wouldn't be the first bubble in a useless commodity to stretch on for several generations. (That honour belongs, I suppose, to gold -- a bubble at least five thousand years old and still going strong.)