If you are wondering how much you will spend here, I will point you some everyday prices so you get the idea of the money you will need for students life.
This are more or less the everyday things you will need if you are Erasmus student, but I will wirte down some advices if you want to save money and save for the next month:
If you follow most of this advices, you can just spend 300€ per month including meals, discos, beer and accomodation. That money will be in most cases covered by your scholarship, so you will have more for shopping or traveling!
This is the definitive guide for a Erasmus or a Student in Bratislava, all info I know about the city will appear here