Buenos Aires city is located approximately 30km from Ezeiza International Airport (also known as Ministro Pistarini International Airport). There are a few options available to get from the airport into the city…
At the airport there are official taxi service providers that provide a fixed and reasonable price. You can book and pay for your taxi upon your arrival. For example, the Taxi Ezeiza booth is inside the airport, directly opposite arrivals. Approach the booth and give them the address where you are staying, then you can either choose to pay ahead of time or at the end of your journey. With Taxi Ezeiza, a cab should cost AR$400 (between US$30 and USD$48, depending on which exchange rate you use). You can pay in dollars or euros if necessary.
Avoid anyone offering a cab who is not from an official booth, because prices are likely to be much higher.
Private car transfer service
Websites such as Dot Transfers allow you to book your private car from the airport in advance: www.dottransfers.com/argentina/buenos-aires
The bus company Manuel Tienda León runs a service between the airport and the city centre., where you can then flag a taxi to continue on to your destination. The bus can be booked via the company website; however the website is in Spanish only: www.tiendaleon.com/resultados/busqueda/bus/ezeiza