To echo what others are saying: I don’t see getting a killer rig right now as the starter path. A 3 to 4-year-old Imac 5k or a (gasp) 8-year-old trashcan is a better machine to start on. I say this as someone who’s using a trashcan professionally. I’ve delivered 4k movie work off this thing, finished 6k shots, and while I’m not going to argue that it’s ultra fast, it’s also a perfectly pleasant user experience.
If you’re gonna put money into anything, Put it into drive arrays, since they’ll be able to move across systems. Here is a thread discussing them in some more detail.