Zurich is pretty expensive.

But there are a couple of 'cheaper' options. The Zeughauskeller ( http://http://www.zeughauskeller.ch ) is decent, and fun, and the prices are fairly reasonable at around 25-35 USD for a meal.

If you want to go really cheap, there's always Bretzelkönig, which has pretty good pretzels, and their hot dogs are pretty good, if a bit shocking looking if you're american. You can find them at a couple of places in the HB and in front of Globus.

Speaking of Globus, on Bahnhofstrasse also has a restaurant on top and an Apero bar in front. The restaurant on top is decent, and the prices were okay. There's also a bakery in front.

Manor on Bahnhofstrasse (http://www.manor.ch) has a decent self-service restaurant on their top floor. The prices are also pretty reasonable. It does get pretty busy at lunchtime.

Migros on Lowenstrasse has a self-service restaurant as well. It's cheap.