Shure SM58, its prettymuch the industry standard for a handheld vocal mic (mainly for live situations¸
Umm in a studio thats prolyl as cheap as you'll get for vocals. Ideally for vocals a large diaphragm condensor is the best. Just go get a cheap dynamic microphone from radio shack or whathever if SM58 is out of your price range, check out audio technica they've got some great budget microphones.