Book prices in different markets...

One of the advantages of subscribing to a VPN service such as Witopia is that you can see things that are hidden from you. Here's an example:

  On the Google Play Bookstore this book is USD$18.99 when my VPN makes me look like I'm in the USA, and and it's AUD$21.98 (USD$22.80 at the time of writing) when I'm "in" Sydney. Electronic download only, yet it's nearly AUD$4 more expensive to download in Australia. I'd like to hear the explanation for that!