Well, I do agree that you might be a little short.
But to answer the OP, first a question : why restricting your choices to Palermo
& Recoleta ? Maybe you should expand a bit your area of research.
To put it in one word : if you live in Recoleta, you are not spending wisely (your limited budget).
There are plenty of nice barrios nearby those.
You could even target San Telmo (if, as a photographer, you could rather like an antique flat with high ceilings than an "all-square" modern one in Recoleta).
Now the budget (you are late 20s, wanting to spend good times in a nice place, without spending too much) :
For one month (min/max) :
- Rent : 400/600$ I would like to know where you can find a 400 dollar a month. Maybe you can post some links?
- Food (eating 5 days/week at home, eating in the street or cheap restaurants at noon) : 200/300$ If you eat at noon every day, you already have spend your 300 dollar. If yo want to spend 300 dollar on food and drinks you can barely eat out and be prepared to eat stuff like pasta(cheap) a lot
- Restaurants (2 times a week, regular ones that provide good meals, without alcohol -multiply below prices by 2 or 3) : 120$ Agreed
- Alcohol : 1 liter of beer = 1.5$, bottle of normal/good wine = 7$ At home?
- Taxis (5 rides a week, assuming you take the public transportation for your everyday's activities) : 60$ 12 peso a trip, that are short trips then
- Public transportation (4 rides a day, 5 days/week) : 20$ Agreed
- Parties/bars/"noche de locura" (if you are in your late 20s, better enjoy your time, right ?) (4 times a month) : 200$ If you don't do crazy stuff you can probally sneak out 6
- Personal purchases (from clothes to a photography book you liked) : 150$ Agreed
- The "unexpected" : 100$ Agreed
- Optional (of course it is optional since you have a girlfriend. Let's assume someone comes here single and meets a charming Argentinean woman) : 300$ Sometimes cheaper, sometimes a lot more expensive
- Medical bills (once you have "consumed" with that Argie girl and discovered she already had 2 kids by the age of 17) : 150$ for SRDL/Hep/Hiv/Clamydae test in a private lab (OK that last one was for fun). That was not fun
Total (without the last joke) : At min, you reach something like 1300/month, and it can easily grow 10/20% higher.
Probally around 2000 dollar
6K sounds like a reasonable amount (just reasonable), like many already state