The Czech Republic tends to be cheaper than the rest of Europe. Public transportation is highly subsidised   (i.e. metro ticket costs only EUR 1 for 1 trip or EUR 5 for 24 hours). Dining out can be super high, as in New York, etc. but can be very cheap as well.  It is possible to eat well for EUR 5 per person but also for EUR 100 per person and everything inbetween.  In the tourist areas where English menu and waiters are a given, the average is about EUR 20 per person for a meal + alcoholic beverages.  Most restaurants have their menu on display so check before you go in. 

Once outside of Prague, the prices drop by about 30%, however, the menu may not be translated into English and no English may be spoken in the restaurant. 

Not all places take credit cards so check.

Prices for entrance fees, clothes, souvenirs, etc. are about the same as in the rest of Europe.

VAT or tax is already included in the quoted price.