My guess would be that they listed the book a long time ago and lost track of it or that their pricing bot has a bug. Or they're humans (one dedicated person can do a surprising amount of book sales, we discovered).

Our experience was that there is no inattentive-buyer market. Those high-priced books will not sell.

edit: I'd add that we didn't like to stock books with low prices like that. There's no margin in the <$5+s&h books you see on Amazon. Instead, we had a big pulper and we'd pulp our 10m copies of "Patriot Games" and sell them to recyclers. My understanding is that my former employers have moved to start making recycled paper themselves and selling that these days.