Your equipment seems adequate. What, if anything, do you think is lacking? What do you feel is wrong/lacking with your vocal tracks? 

You do realize that even with the best equipment, your vocals won't sound "studio quality" if you aren't recording in a space with as good acoustics as a studio.

Ok, you seem to have a bout of GAS and just want more equipment, so I'll play along. 

I like tube pre's and have even built a few of my own. SM7 + a tube pre can be warm and syrupy sweet as you want.

You can get a decent (if not better, ok, different sounding, and much better featured) 2-channel tube pre for moderate cost, like the ART MPA-II or TPS II, especially if you want some tube "warmth" going in. Handy to be able to adjust input impedance with dynamic mic's too, can make a big diff sometimes, although I doubt it's very critical for rap. 
Or just a single channel or lower spec version, to save cash. ART also offer a combo tube pre and comp which is cheap and cheerful, and nice for guitar also. Other companies offer similar.
A variety of pre's is always nice, especially if you ever need a different vocal sound OTB. Heck, even a Presonus Bluetube will give you more options at moderate expense.


And get some decent monitors as others have suggested. And some good cans too, if you don't yet have some.

So, my recommendation is, listen through some tube pre's on decent monitors and through good cans, and compare to how it sounds through your Scarlett/Konnect pre's.

But seriously, I wouldn't worry too much about getting to "studio quality" with your rap vocals because I doubt anyone but you or some label exec is going to notice anyway. Maybe you should aim for "PA system quality". 

Sorry for - what
I was just sayin'!
But like I told ya,
I was just playin'!

The real secret is....of course.... in learning how to work with it to get the professional results you want..... the gear is good.....the learning is as important if not more so then the gear...having good gear is a good start.

Might want a reflexion filter, and a mic that sounds good for your voice, whether it is a cheaper mic or an expensive mic. Pre-amp or maybe better - a studio channel also useful on other instruments. http://www.sweetwater.com/ or whereever musical equipment is sold.

There is also some youtube videos on microphones also and what people do - look up microphones there.

I think you're actually going into it a bit backwards.  You say you're not into monitors, so I have to assume you have high quality ones now, or you don't realize that if you can't accurately hear what you're doing, you won't hear what better equipment is actually doing.  The space is next, so you monitors translate to you, what's going on.  After that, everything else is really waaay down the list.  The proof is all the great recordings using cheap mics or equipment, but attained the desired results.
 
Now...let's say you have monitors and space covered, you're looking for that last detail that is going to help...as we're actually on agreement now that you can reliably hear what you're recording.
 
I think there is a reason why certain pieces of equipment sound good on most everything, such as using an 1176 compressor or LA2A or one very flattering mic pre for YOUR voice.  I might be inclined to spend your entire budget on one of those first, as you'll get your money back if you don't like it.... and yes use it while tracking.

If you don't heed
What we've been sayin'
For what you don't need
You're gonna be payin'!

You probably will want some kind of mic preamp with a SM7 due to the low gain characteristics of the mic. I thought mine was defective the first time I used it but quickly found that it came to life when paired with a decent pre. The room is also very important also as already stated by many. A moderately priced vocal booth may be a good option.

The room is a huge factor.  You can ruin good recordings by capturing some unwanted standing waves that simply can't be EQ'd out.  You can always buy a reflexion filter to take care of that if don't want to deal with the room right away.  At least you won't wreck good vocal takes.  

No, no, no, don't worry about the room, 
Spend all your cash to buy more boom!  
Record your vocals like all the pro throats-
Inside a closet full of winter coats!

For rap, Avalon 737 and an SM7B. Done. Right in your price range.