You can eat at a number of differnet price points.



We usually have the hotel breakfast and a casuale but sit down lunch - no picnics of sandwich from a market and allow $25/$ 30 per person for that. We allow about $75 or so per person for a pleasant dinner with 2 courses, wine and coffee with often a shared dessert.- but in each city we do one splurge meal for which we allow $300 per couple. We are not foodies but do enjoy good food and like a relaxing 2 hour dinner unless we are doing an ballet or opera or whatever that night.

Obviously you can spend much less depending on your eating habits and what venues you choose.

You can get the sightseeing prices from web sites so there would be no guessing on these items.

Food has such a huge price differential that it's hard to say. In Prague I spent between $10 and $25 for dinner (including a couple of glasses of wine); $10 to $13 for lunch (salads). If you drink soft drinks that will add tremendously to your budget. Stopping for coffee, pastry, wine also increases what you spend. I'd guess at $150 per couple per day.

<< I have no idea what food costs in these cities >>

Guide books give you this information but it seems that no one reads guide books any more.

I live in Budapest and just moved here from Bratislava...Budapest is a great value now given their weak currency. My daughter and I ate in a very nice restaurant near Liszt Ferenc Ter... We each had a drink, appetizer, meal, and she had dessert. The bill was 45 dollars (US) with the tip. (This is nearly 10000 forint... The exchange rate takes some getting used to).
Vienna is a bit pricier.... But has a lot of options if you need to save money. We go to Vienna every few months (an hour by bus from Bratislava).... Similar meal to the one I described in Budapest would run closer to 100 dollars. That said, meals in Vienna can be heavy and we would rarely order an appetizer and dessert. Our favorite restaurant with two drinks and two meals is about 50 dollars.
Prague is all over the map... Do not eat within site of the old town square. We stayed and ate in the Andel area... Typical Eastern European beer garden... Two dinners two beers... Twenty bucks. I have written up all three cities on my blog: www.worldinbetween.wordpress.com. Enjoy! (And consider a day in old town Bratislava,!)