There are a few quotes I wanted to add but I'll just say what I want to say...
First, we need to know what you recording chain even is. We don't even know what mic you have now.
Also, it is highly likely that with a mic under $500, you will hear a huge gain in quality with a better preamp.
Someone else asked why you want a condenser so bad and not a dynamic...well, He obviously did his homework and decided to get a condenser, so stop worrying about why and answer his question instead of trying to make yourself sound like you know something special about choosing a dynamic over a condenser for vocals. I'm tired of hearing that one random person trying to bring up the opposite scenario just to bring it up. He said he wants a condenser so recommend him a condenser...assume he has done enough research to ask for a condenser instead of messin with their head. Nothing wrong with a condenser...it is prefered in my book anyway along with everyone I've EVER recorded or has recorded me in a studio (not live). I'm not about to get into the reasoning...i've said enough here that has wasted our time.
Someone else mentioned the Rode NTK, N1000, and NT2A.
The NTK has bang for the buck. However, it is known for having the highs a little too sylabant. Nothing you can't correct in the mix, but there are other options. The n1000 doesn't have the clarity of the NTK, but obviously doesn't have the problems with the highs.
The NT2A is AMAZING all around especially for the price. However, there is one mic that trumps them all from Rode that is under $1k
The Rode K2 screams vocal clarity without the nasty highs. Not to mention a natural warmth to whatever is going in. 3 different polar patterns. I recommend cardiroid for vocals, but you definitely want to experiment because its variable meaning you can blend two of the polar patterns to focus the vocals differently.
http://www.zzounds.com/a--2676837/item--RODK2 More than one occasion from pros and amateurs think this mic is actually on par with mics in the $1500+ range. Commonly hearing that a u87 nueman is what beats it in the $2,000 under range. I'm sure there are other mics to consider, but for $700 bucks, not more than two or three.
Someone mentioned
the neuman tlm103. This is the same mic Ryan Leslie got big with. Not a fan...at all. Sounds harsh on his voice, sounds harsh on MANY voices. The highs are just over exaggerated and it creates two things...incredible clarity, but a slight, sharp buzz on certain words. A $1,000 mic shouldn't be doing this...However, this mic is perfect for certain people who lack natural harshness to their own voice...I don't know anyone personally who doesn't have some type of their own characterisic resonance that need to be brought out anymore than it is...the tlm103 does that and that's the problem. Great on a dull, neutral voice.
Again, let us know your recording chain. You will probably benefit just as much on upgrading your preamp.