Some of those are plain stupid from even a greedy money-grubbing perspective too. Reap The Whirlwind and the Worlds of DS9 books are both middle books in a series. RtW is especially a problem as it's book three, and the entire Vanguard series makes little sense without it.
You limit the availability of them by charging silly prices and you risk putting people off the entire series. For the sake of getting twice the money for one book, you risk putting someone off buying the next five books in the series. So if the price puts (I think) one in six people off buying it, you've then wiped out any benefit from selling at a higher price.