I think we're missing some of the picture here so I'll ask some relevant questions.
- What daw are you using and how much experience do you have recording?
- What's the goal? Release or decent demo?
Reason being, you're talking to people (others not me) who are working on hip-hop songs to potentially be released to the general public and their bar will be much higher than what you may be shooting for or even need.
Honestly... until you get more comfortable engineering there's absolutely NOTHING wrong with tracking a rap vocal without compression, with a decent prosumer pre, and compressing it in post using plugins. Will it sound like Tony Belmont tracked it with a Neve pre and a LA2? No.
Will it sound as good as 75% of self-made home-produced rap vocals? Sure, even better if you do it right.
The WORST thing you can do (imho) if you're new to recording is go out and buy a bunch of expensive gear that you have no idea how to use yet. Plug in your mic (when you get a pre) and track your vocals. Go from there. Your "bar" is not where their bar is, nor should it be right now. P.S. I asked "what daw" since - subjectively - some will have better comp plugins for heavy hip-hop compression than others.