Total rip off IMO. does anyone actually use it?

Here's an extreme example, I found a book over the weekend, Ecology of Java and Bali - its part of a larger series, anyway at $11 new for softcover or $30 for hardcover I bought it immediately. I wanted to find out about the others in the series so googled looking for its ISBN number....

well look at the price here for Amazon, same book, second hand, hard cover!



that says $191.56 + for those that caint read,...

Had I chosen the correct book ? hmmm, lets try Cambridge...



only $20!!!

So what is the deal with Amazon? is this how they make their money then?

Well I wont be using them then, if I dont know the correct price of a book in the future!