you asked about food cost, right? it depends on how much and what you eat.. but I think 500QAR is a bit low. If you like to eat good delicious meals (I mean at home), be ready for at least 1000QAR a month. I would say, food+ house keeping +some small things around is about QAR2000 a month, without car and accommodation. Then depends on how large you like to live.. Some people live with QAR 1,500, for some people QAR 15,000 is not enough..