I took the bus service to/from EZE (didn't see the need to spend extra for a private car since I was staying at the Marriott which is right near MTL's office). Going into BA the fare was USD 3 (12 pesos); coming back to EZE it was 15 pesos (just checked both receipts).

I still find it odd that the lady at the airport insisted on giving me the change in USD, since she had no problem giving me a receipt in pesos. (I figured it would be a good chance to get my hands on some small bills - always a problem when arriving in a foreign country.)

While I'm here, there's another thing I found odd at EZE airport. When I checked in for my Delta return flight to the USA, I was given a blue voucher that said, "This voucher proves payment of the airport taxes." I thought, "Oh, good - the tax has already been included with my ticket." But when I got to the tax counter to claim my sticker for boarding, the man behind the counter asked to see my ticket. I produced my e-ticket receipt, whereupon the man told me I still owed USD 13. So, anyone going to EZE, beware: Even if your airline says you've paid the airport tax you may still need to pay the tax.