This tip was given by Bruno in DealExtreme community on Orkut: é um complement (plugin, addon, etc.) for Firefox that displays prices in real DealExtreme or any other currency selected.
He picks up the Google listing (type “dollar” no Google para testar) and any product that you view will appear with the price in the currency chosen and optionally also in dollars (should be the default option). You can also set an extra percentage on the value, to add the PayPal conversion rate, the IOF and / or the conversion rate of the credit card company.
Moreover, it can also convert imperial measurements used at DealExtreme (inches, oz, pounds and the like) that are used in the United States and England, the measures of the international system (centimeters, grams, etc.) used in Brazil and throughout the rest of the world. No doubt an excellent resource.