I rented a loft for 6620€/year. It's mint condition and it's in the outskirts of Barcelona. I'm 12 min in subway to the plaza Catalonia and in 7 min using the train or 20 mins in bus. To be honest, I would never never again will rent in the centre of the city. It's expensive and all buildings are antique, without the proper commodities.
If you want to come Barcelona, check the outskirts, get a scooter or enjoy the Barcelona transportation system. It's wonderful.
I want to add some more info about living in Barcelona.
The weather is magnifique. It barely rains all the year. You can go mountains withing 2h car travel if you want to enjoy the snow in winter.
Eating can be really cheap IF you go to the supermarket, buy all the meals and cook yourself like I do, I saved 300€/month doing this instead eating outside. If you can compile rails, you can be a chef, :). I do buy the meals and stuff for around 90€/month. That includes the 40lts of water i buy. Then daily i try to buy meat, fish or vegetables for the week and it cost me no more than 220€ month.
I pay 90 euros electricity, 30 gas and 40 water every 2 months. 60 euros for 100mbit fiber connection + phone and mobile and that's all.