Apparently I haven't been paying attention to the price of textbooks

I went to submit my order today for a textbook for the Principles of Micro class I am teaching in the Spring.  I chose Mankiw's 6th edition because 1) I am lazy and all of my notes are from Mankiw and 2) I am lazy.  So here is what I found when I was looking up the ISBN #:

Principles of Microeconomics, 6th Edition
N. Gregory Mankiw Professor of Economics, Harvard University
ISBN-10: 0538453044  
ISBN-13: 9780538453042 
528 Pages  Paperback 
©2012     Published
College Bookstore Wholesale Price = $163.75

$163.75. 

Really? 

I may have to change my stance on price gouging.