In bahrain you can get local currency from any ATM using your banklink/pass or visa card. Local currency is Bahraini Dinar worth about 2 Euros..
However unless you have a prestamped visa you need to buy one from the guy who stamps your passport and that costs 5 Dinars cash. So you need at least that much even though if you search hard enough there is probably an ATM before passport control. They might also take credit cards but i've never tried.