Well, I'm not sure what's the location of your data source and in what format you need the data, but from your description I can make the following recomandation:
Use a service like:
https://openexchangerates.org/
and afterwards parse the response with a JSON parser (like the official one):
http://docs.python.org/3.3/library/json.html
and Voila you have the currency.
UPDATE
If you really have time and as the time passes patience to modify it, you can take whatever site you want with a visible exchange rate and write a HTML parser:
http://www.diveintopython.net/html_processing/extracting_data.html
This solution gives you freedom (basically you can query whatever you want) but if a site changes... well you have to update your code
UPDATE 2
You can use a very simple trick and a very simple html from google. Try to call the following link:
http://www.google.com/finance/converter?a=1&from=BGN&to=AED
and you will get a response for free, without any key, but be aware that this is not fair play especially when you are polling the service many times a minute!