As far as drinking goes, I didn't go to any bars, but any restaurant (some with bars in them) that I went to had cheap beer, even if the food was a bit pricier. One restaurant I'd def try is Pizzeria Kmotra (V Jircharich 12, Praha 1.) The food is excellent and reasonably priced. Bohemia Bagel (4 locations including one near Charles Bridge and one near Old Town Square) is also good with some items at more reasonable prices. However, as an American, the price of bagels in Europe in general shocks me, so you may find most of the prices good
A couple of traditional Czech restaurants that come highly recommended (and are supposedly quite inexpensive) are V Cipu (V Cipu - off of Panska) and Ferdinanda (Opletalova and Politickych veznu), though I haven't actually been to either one of them myself.
On a side note, while I've yet to get this info into the wiki, I have added most of my info on attractions and such, so check that out if you're interested.
Cheers!