There is frequently a system where they sell an international version of the book for significantly lower cost. In order to prevent americans from simply purchasing the international version, it will often have substantial differences. So simply looking up the price of the same book may not show you what would typically be paid in another country.
The publishers originally had a great system, back before the internet was alive and kicking - they'd sell the textbook in the USA for $bigbux, and sell the exact same one in India for $cheapasfree - basic standard price segmentation, charge what the market can bear in each market.
But then the internet and cheap shipping appeared, and suddenly people in the USA realized they could get the same textbook by ordering it from someone in India, and pay $cheapasfree + $shipping.
And ever since the publishers have been trying to get back to the original promised land.
They could have lowered the price in the us enough to not make it worth getting a cheapo version which the quality is frequently worse. What many did instead was to lower the quality and sell at high prices, in many cases books have poor binding, poor print and editing and so on.
