What is Europe's Cheapest Capital City?

I would like to know what the cheapest capital or principle (I mean e.g. Krakow - not a capital but culturally as important as Warsaw) city in Europe is in terms of food, rent, travel, etc. I've seen league tables of the most expensive cities in the world, but I need to go and live somewhere culturally interesting and cheap. I'm looking at Eastern Europe, Baltic and Balkans - Budapest, Bratislava, Riga, Sofia, etc. Any information generally on cheap rent in attractive European cities would be welcome. Thank you!