How much does it cost to live in South America?

You can spend as much as you want or as little. Staying in hostels shouldn't cost over $10 or $15 a night, depending on the city. Food can be had for less than $10 per day. Many people that live in South America feed their families for less than that. On the other end, in almost all cities you will find hotels that rival the US for cost. And the same is true for food. Travel is generally pretty cheap, using a bus to get between locations. Taxis, generally, are reasonably priced, by US standards. Don't be cheap with the buses. The safer ones usually cost a little more.