Well, that's the price that you might pay if you look for that book on the Barnes & Noble website, e.g.,
On the one hand, this is the result of me restricting B&N from my sales channels. (I had signed up for it, but their discounted price -- $13 -- was only possible because they cut my royalty.)
On the other, it's a "bad shopper" tax, if someone can't find TEoA at its normal $20 price. (How is it possible that someone has NOT heard of TEoA yet! :)
Do you know anyone who is so lazy as to not look for a lower price on a book?