In my opinion if you're almost 30 years old, well educated and you are in Sofia most probably you live in a rented accommodation and receive around 1000 lv. per month (unfortunately there are young educated people in Sofia who work for 500-600 leva). Of course there are people who live with their parents, but to be 28 and still live with your parenst ?! (I can't even imagine it.) So here's my list:
rent - 400 lv.
bills (heating, electricity, water, internet, cell phone) - 150 lv.
transport - 50 lv
So you'll have 400 lv left for food, drinks, coffee, pocket money, cosmetics, sports, clothes, shoes, books or whatever you need to buy. What a challenge, ha?