Or I could say, the person who's charging $30 for it on Amazon was the first one to put a used copy on the internet, and thought they'd see what the market would bear.

As far as I can see, there are only a couple of copies available in Teh Entire World. You should try to foist yours off on an unsuspecting antiquarian as VINTAGE PULP. Hee.

Oh, Patterson...one of the more reliable hacks, but once an author starts collaborating with someone, I handle with reticence.