Sometimes it takes just a few hundred meters to find a great local place serving perfect beer but for normal prices.
Organise your own cheap pub crawl  by avoiding the tourist traps and crazy beer prices by using the great interactive and unique beer price map of Prague on nelso.nl (available in more languages) or you can try out Prague's organized Pub Crawl, which takes groups to several bars and gives away free alcohol for the first 90 minutes.  The site is thecrawl.cz and they help travelerss find cheap bars in the center.  

In a number of the places on the map you'll be able to find the true bohemian atmosphere, some live music and some great snacks to go with the beer !

Enjoy Prague like the locals do !