How much do I have to invest in mining RVN to get roughly $4-5k / month??

I'm talking with some friends about putting some money together for a smallish mining operation, and I've wanted to get into mining for a while. Anyone have any good resources for us , and have insight on how much we should expect to spend on a system that produces our goal of roughly $4-5k in coin when done?

Really appreciate feedback and support!