As someone who used to live in (very expensive for non-basic necessities, cheap for basic necessities) São Paulo and moved to (reasonably cheaper for non-basic necessities, way more expensive for rent and food) Boston, when I went to Prague it felt cheap.
I found 4-star hotels in Prague 1 for the price of not-that-great hostels in London, €18/day. I'd go to a bar or a club and pay €1.50 for a pint of beer. I could get a day pass at the tram/bus for Czk 100 (about €4). I heard that a 2-bedroom downtown goes for about €600-700. Internet would be €50/month.
If someone can give more accurate prices or tell me how it's going for Budapest, I can guarantee you one karma point. :)