Open a FOREX account with an online brokerage such as Interactive Brokers.
Will charge a $10 monthly account fee, but you can trade pretty much at the interbank rate (i.e. the rate you see on google) with a $2 fee and free withdrawal into a bank account in any country once a month.
Will be cheaper than ANY currency service or bank as even with the best currency services you tend to lose about 0.5- 1% on the interbank rate, and as much as 3% with the banks.