What's the best mic for rap vocals?
Ridicule!
No no, its true - this really is an insanely complex thing to ask, in the hopes of a simple answer - however, everyone has been here at one point or other, so I won't go on, at least not in a sarcastic sense.
The straight answer is , as stated - there is no microphone designed for one type of music over the other - it is simply a matter of matching a mic to your voice, and as much as this might not seem important, there really is a big difference.
A mic I own that sounds great for my voice has sounded like crap on everyone I've ever worked with / played with. I hang onto it because it works for me.
But if you are looking for a general workhorse mic, search the mic forum for "vocal" - you should get about 9,000 hits for threads discussing just this topic. Sort by most replies, and start reading.
However, to get you started, I can suggest a few things, one is that you don't necessarily need a condenser. A condenser is more apt to expose the low-quality of the room you are recording in. Two dynamics that get a lot of use around here are the Electrovoice RE20, and
the Shure SM7-B.
As for condensers, many find the Rode microphone line to be harsh, and I tend to agree. The only Rodes I like are the NT3, which is better for live than studio, and the K2, which is out of your price range.
The Studio Projects line of microphones gets good praise around here, among the cheaper condensers you can find these days. Again, I am just tossing out general brands here that people seem to get along with in as many settings as possible - since I figure you won't have the option of doing a 10-mic shootout to find which one suits you best. I know all about the "try before you buy" issue, since you can't return mics to many music stores nowadays. You can try in-store, but that isn't going to be representative of the rest of your signal chain, so it can only get you so close to knowing how it will work.
Like I said, search around, and then come back asking questions about, perhaps, a narrowed set of choices.