I did BA-MVD on Buquebus (Francisco, not Pablo ;-)) last December, the ferry was nice and fast, cruising speed was 60 mph on my gps device. Check the price on BuqueBus.com, I paid around 600 ARS for OW, it will be a little cheaper if you use ColoniaExpress and you may save u$s40~60 but it will be 4:30 hour trip (vs 2:15 on Francisco).