haha you better get going if you're running late instead of asking how much it costs here ^^ depends also on the value, guess if it's important to be on time you will be willing to pay a higher price, won't you? but since you are posting here before going, I guess the Cab will be too expensive for your concern, as long as we haven't been timetraveling to the time that SteveinBsAs described
A Friend invited a lady to his flat for drinks he suggested paying her taxi fare RT from Belgrano to Puerto Madero, the fee was $140 ...!! hope it was worth