Hello, I search for the type of trip that want to make why? Prices vary much if the passage the ship direct "the quick three-hour" the rest are via Cologne you got an hour of ship and then you must get on a bus from Cologne to Montevideo and values change. So there are other value also can be fixed if you are first or tourist. I would advise you that if you are in Buenos Aires, you approach Buquebus and reserves in cash and if not buy one of two or three direct ship schedules! Also you got Buquebus flights. But I doubt that in Uruguay you sell in Argentina currency, they will sell in Uruguayan Pesos or dollars (do not know very well). But it is logical that each country has its sale in its currency. And perhaps you can arrive and get the passage, but is an orange blossom send without knowing if there is place, if you have time you can go a day before and now. I hope you serve and your trip is good.