Amazon Arbitrage

It turns out the same item might have a completely different price at Amazon.com and Amazon.co.uk (or presumably any one of Amazon's other five country sites).  I'm not talking about a few dollar or percentage points either: I recently purchased Hops and Glory: One Man's Search for the Beer That Built the British Empire, as a chanukah present for one of my beer-loving friends.  The page that suggested it provided a link to Amazon.co.uk, which I thought was odd because it is a US-based site.  Searching for the same book on Amazon.com I found the following amazing result:  The Amazon.com price was more than twice as expensive, even after shipping was factored in.  See pictures below (note that the UK price includes shipping and gift-wrapping:

In this global era, when accessing international catalogs (websites) requires only the conscious effort to do so, it makes you wonder what else you could save money on by ordering from abroad (and whether there isn't a business idea here).