Hi. We spent a few days in Madrid last April. I can't remember specifically how much food and drink cost, but I can remember that it wasn't particularly cheap. Obviously it will depend on where you are eating/drinking though!
As Corinne76 says. It wont be cheap.
I've not been for quite a while, but when I was there (which was many times, mainly working) if you keep away from Sol, then you should find prices more reasonable.