I apologize if this has been previously answered, but I am going to Mendoza in about a week and have a question about payment at the wineries. I understand that each winery charges around $10 USD per person, and that lunch at Ruca Malen and Andeluna are somewhere in the area of $65-70 USD per person. Do all the wineries prefer or expect to be paid in USD? If you pay in pesos, do they use the official exchange rate or the informal rate? I'm just trying to budget and also plan how much I need to bring in USD for my trip. Thanks!