I posted the info below in response to a recent question. Torii has suggested it would be usefully posted as a separate topic, as it seems to be a frequently asked question, so here it is:
We just came back last week. The cigarette prices range from about 55 crowns for local brands up to about 85 crowns for brands like Marlboro and B&H. 200 of premium brands were 820 crowns in both the local supermarkets and at the airport. We normally smoke Royals, which are the same sort of strength as B&H (but cheaper), and we bought Winstons at Prague airport - 200 for 640 crowns. If you buy at the airport make sure you've got enough crowns left because although you can pay with cards or sterling or euros, you'll get stung on the exchange rate!
We paid between roughly £13 and £20 a head for 2 courses, 2 drinks, 2 coffees in reasonably good/mid-range restaurants. Beer prices varied from 27Kc (in Mala Strana) up to 40Kc (Wensceslas Square), wine is a bit dearer but not too awful.
It is probably more expensive that it was, but this is mainly due to the awful exchange rate and at least it's still cheaper than here!
Be warned, if you want to smoke in the airport before you fly home, you have to buy something in the bar to be allowed to smoke in there (only place you can) and they were charging 145Kc for a beer!!!
Hope this is useful, enjoy Prague!!