The RNC is a fine compressor... not only for the money but purely as a compressor. The fact that it's less than $200 is a bigger reason to get it. If you just want pure compression, where the compressor is not being used to color the sound (as many higher end compressors are used), then the RNC is your ticket until you want to add to your rack.
Back to the mic--personally, I think you
can make the SM7 work, but let's face facts... part of the 'sound' everyone is looking for when doing rythmn-oriented material is the pop, pop, fizzy fizz of a condenser. IF you were doing just a rap thing, I'd say save your money and just deal with the SM7. But since you're doing some singing and it's 'rythmn-oriented' (pop, dance, pop-rap, r&b) then everyone identifies the sound of that material with a condenser.
In its price range, the C1 is about as good as they come. If you're going to upgrade eventually to a Soundelux or a Neumann, you may want to cheap out and get an MXL V67. I've had one of those in the past, and it is a very decent mic
in it's price range (less than $100). This way you can get by with decent vocals for the upcoming session, your mic will look like a more expensive mic, and you can put your hard-earned dollars towards the mic that you really want (and I want you to have--a Soundelux U195).
P.S. I've owned a C1 for several years and I like the mic... I did a lot of stuff on it. BUT, when
my Soundelux U195 came into the studio, the C1 hasn't seen the light of day since. In fact, I just sold it on eBay. Go hard or not at all. Save your money and get by with a V67 ... or you could always just make due with the SM7.