I've been there and it's a beautiful city. Everything was very affordable when I went, but it was in 1993 last I was there. I bought a round of drinks for an entire bar for under $15 - the whole bar. lol I'm not sure what the exchange rates are now or how the economy is faring there, but I do know a lot of models are in the Czech Republic - some fashion and some porn/adult. It's much cheaper to get models there than in most of the western European countries.
I went to Prague to study architecture, though, but the nightlife was great. Cheap drinks, lots of friendly people, and the city is gorgeous at night (and day, for that matter). Just be cautious as with any city to which you've never been, and pick up a quick-read city guide at your local book store before going, or research it online. Every city has places you're best off avoiding (dangerous areas, etc.), so do a bit of reading first.
My :2 cents:, and have a great time!!!