Live Stage Performing
Did you know that some of the best vocal microphones can be had for under 0? This is not to say the very high end mics that sell in the 00-3000 range aren't good but from my experience sometimes when compared side-by-side often times the 0 mic is as good and sometimes even better depending on the person using it.
If you're looking for a microphone for singing live on stage the Shure Beta 58A is very good. This is a considerable step up from the long time favorite Shure SM58 which has become an industry standard dynamic vocal microphone used by many singers in almost every situation around the world.
Check out the specs for both these mics;
SM58
Pattern: Cardiod
Freq: 50-15K Hz
Output: 1.85mV
Weight: 10.5 oz
Beta 58A
Pattern: Supercardiod
Freq: 50-16K Hz
Output: 2.6mV
Weight: 9.92 oz
If your budget can stretch a little over the 0 point then you should consider the Shure Beta 87A which has an even better proximity effect for live singing. Proximity effect refers to the distance your mouth is from the end of the mic so with the Beta 87A you don't need to "swallow" the mic as much.
Recording Studio Mics
Now for singing in the more controlled recording studio environment you should take advantage of a large diaphragm microphone to give you a bigger tone and generally much better quality vocal sound.
Still, for well under 0 it's tough to top the Behringer B2 Pro which is a high quality studio condensor vocal microphone with a large 1" dual diaphragm.
And did you know that Marshal, the famous guitar amp company makes some great microphones as well? They have a great pro studio quality vocal microphone for under 0; the MXL.007 which is a large diaphragm stereo condenser microphone giving microphones that cost 3 times as much a good ride for the money.