Not clear what is "more pricey than they expected" anyway here the living cost is not cheapest among similar countries in South America even it depends on your actual income / living cost.
For example (including rent + expenses, car expenses, daily life, food, etc) not doing so many crazy stuff you´ll need in my opinion a minimum of usd 1500, that´s for someone living alone in the suburbs, cooking your own meals and again not doing a lot of crazy things. If you´re a tourist and in a saving mood you can live with less of course but this is for you to have an idea.
Here the 1,00 dollar is 15.50 pesos aprox.
For example for a dinner for 2 with wine + dessert in a nice place you have to think about usd 100 + tip or more.
There are cheapest options like Mc Donald´s, a combo (big) is more or less usd 10,00... there are cheapest options
For having a better idea you have the Big Mac index, is a comparison tool where you can check the price of a Big Mac among countries (search online).
In our case (Argentina) now is ok to use that index, in the last government the price of Big Mac was "manipulated" and was maintained at a price a lot cheap compared with other burgers / combos. That was in order not to reflect the real state of our economy. Nowadays looks like the issue was solved.
Any other question you have, just ask