Amazon have replied, but it's not even remotely an answer to my question. Here:
Thanks for writing about the price difference on Kindle content.
Strong customer feedback like yours helps us continue to improve the service we
provide, and we're glad you took time to write to us. I'll send your comments to the
All items available in the Kindle store are listed in U.S. dollars (USD), and the
availability and pricing of titles from the Kindle Store varies by your home country
If you're browsing in the Kindle store and the country or region displayed in the
upper right-hand corner doesn't match your actual home country or region, you may
see a different price during checkout that is specific to your home country or
You'll also find helpful information on our Using Kindle If You Live Outside the
United States Help page (http://www.amazon.com/kindleworldsupport).
I hope this information helps. We look forward to seeing you again soon.
"The availability and pricing of titles from the Kindle Store varies by your home country or region." Yes, I believe that was the issue in the first place. It's not like I was unclear about the situation, they've just chosen to give me a blank response.