Probably around 200-250 euros per day depending on your budget. But I think in Barcelona you can have a great time if you stick to a budget of 150 euros per day or less. But I think travelling in Spain with a lot of money is not such a good idea as you will waste lots of money on accommodation and souvenirs. Also, the culture and cities are not that expensive, you can spend less money there too.
What do you think? Did we spend too much? Did you ever travel to Barcelona and kept track of your travel expenses? Please share your experiences with the costs for a weekend in Barcelona.