Hi, maybe stupid question, but I don't know if there is minimum amount for IBAN transaction?
for example, I sell at Mtgox or Internsango (or anywhere else) 0.5 bitcoins and I get 2.5 euro, then, can I transfer so small amount to my IBAN number?
I don't know the exact fee, but the exchange subtract the fee to process wire transfers, and your bank may assess a fee as well.
So, let's say the fee is 5 EUR. That means for a 100 EUR withdraw, you are paying at least 5% in fees.
I believe BitStamp is known for its lowest cost for SEPA transfers. Dwolla is the lowest for ACH (USDs to a bank in the U.S.). So depending on where you bank the recommendations will vary.
It is better to accumulate your fiat account balance, then make only larger withdawals in batches, or to use bitcoins themselves for spending, or do something else like withdraw to PayPal (e.g., https://www.spendbitcoins.com/convert