The lowest cost was found in the US ... mostly. Certain models cost less in Hong Kong, but as the author notes, that could be due to exchange rate fluctuations. Prices were significantly higher in South Africa. For example, an entry-level 13" MacBook Pro 2.26GHz in South Africa retails for about the same prices as a mid-level 15" MacBook Pro (2.53GHz) in the US. Note that Apple does not have official representation in South Africa.
However, the highest prices were found in Brazil (where Apple does have official representation). As cmyplay notes, "For the amount to purchase a top-of-the-line MacBook Pro 2.8GHz in Brazil, a person could buy two of the same machine in the US." One Brazilian commenter noted that Brazil's import duties and sales tax, especially on electronics, is very high.
Good work, cmyplay! Your graphic is beautiful and offers a perspective we might not otherwise have considered. Make sure you visit the post to see the full image.