First of all: the choise of a vocal microphone for a singer is an individual choise. It is, like any instrument, something of personal taste and feel. You can pick a good quality mic from a list you find on the net or reccomendation from experts. his will however not guarantee you that that mic is the ideal mic for you! You will have to testdrive some mics in your budget to be able to pick your favourit. Be sure to try both dynamic and condenser type microphones!
(for all guitarplayers: which guitar is the best?)

Having said that, here are some mics and my opinion about them:

- Shure SM58: Good quality dynamic microphone with a clear sound. Used a lot in rental situations because almost anyone can use this mic without any problem. (the PG-series are the budget versions of the Shure microphones: not the same standards as the originals.)

- Shure SM57: Dynamic microphone much like the SM58, used mainly for instruments. Although used by some as a vocal mic I would not reccomend it. Reason for this is the fact that the SM57 doesn't have a built-in popfilter to keep moist (spit) from the capsule.

- Shure Beta 58A: The professional brother of the SM58. Tends to sound a bit warmer.

- Shure Beta 87A: Good quality condenser microphone. Like with all condenser mics, this one requires the singer to have microphone technique. Another thing with condenser microphones is the fact that they need Phantom Power. Make sure your mixing desk can provide that!

- Sennheiser E 845: Good quality dynamic microphone. Comparable with the Shure SM58, but slightly warmer sounding (and much nicer design )

- Sennheiser E 945: Professional version of the 845. Haven't tried this one myself yet.

- Sennheiser E 865: Good quality condenser microphone. I've been using this one (the wireless version) for about 8 or 9 years now. One of my favourit mics!

- Sennheiser E 965: When my 865 dies someday; this is the replacement mic for me.

- AKG D7: Dynamic vocal microphone. AKG makes some pretty good mics (I love the AKG C451 and D112) but I don't like the handling of their vocal mics. This has nothing to do with the quality, just my personal feel.

- AKG C535 eb: Condenser vocal microphone. See remarks on the D7.

- Audio Technica AE4100: Very good dynamic vocal microphone. This one has a cardioid pattern. The AE6100 has a polar pattern. I would reccomend the AE4100 opposed to the AE6100.

Audio Technica AE5400: Cardioid type condenser microphone. This one is very easy to work with, you almost only have to think your lines and this microphone will pick them up. Great microphone.

The there are brands like Rode, Neumann etc who make excellent microphones. It all boils down to personal taste and feel. Not every microphone is suitable for your voice. You will have to testdrive several of them. Take someone with you to have a listen also.

Like Don said: There are a lot of counterfeit microphones on the market. When you buy from a descent store you are almost sure to get the original product you paid for. Buying from private persons on the internet...well, let's say you won't be the first to end up with a cheap fake microphone.