I don't think this is viable for the 'guy in the street' because you don't have access to 'proper' exchange rates. Our company spends millions with Foreign companies and we have access to proper trader currency rates. Often these are a couple of percent better than the guy in street sees i.e. the 'spread' is small (difference between buy and sell). The average Joe will get a rubbish spread so unless the exchange rate shifts by a great deal then you won't make any money... you'll loose it in the spread.