i was there for a month in february volunteering and definitely had a budget that i had to stick to!
i didnt go out
a lot but i did like to have a drink or 2 (

hehe) here and there, went to a couple of movies, went to a billiard hall a couple times a week, did a little bit of souvenir shopping, explored the city on my own (no tour guides), took taxis at night and hit a few discos for some dancing and raggaeton
i was staying in the zona colonial and i ate out a lot because i didnt have a place with a kitchen but i stayed away from more expensive places like the hard rock and opted for the smaller, local restaurants and always found plenty of cheap and good meals from street vendors. breakfasts were included in my accomodations so i only really had to worry about a couple of meals a day.
i kept to a budget of about $50 USD/day and still had some money left over when i got home.
hope that helps!! have a great time!