Any price printed in this guide will be wrong by the time you read it. That is not sloppiness, it is the exchange rate, and the correct response is to plan around categories rather than numbers: which meals are cheap in relative terms, which are not, and which are worth it either way.
Friday evening to Saturday
Arrive and do nothing ambitious. San Telmo on a Friday night costs almost nothing and gives you the register of the city. Saturday morning is Recoleta and the cemetery, which is free and takes longer than you think, then the Ateneo Grand Splendid because everyone goes and it earns it. Lunch at a parrilla is the meal to spend on. It is still cheaper than the equivalent anywhere in North America, and the difference in quality is not close.
Sunday
The San Telmo market fills eleven blocks and you will not get through it. Go early, buy the leather thing you are going to buy, and be at La Boca by two. Caminito is a tourist set piece and worth exactly forty-five minutes. The last of the money goes on dinner, late, somewhere in Palermo, at an hour that will feel wrong for about two days and then stop feeling wrong at all.