Your video cards are one of the most important. Make sure it's nvidia gtx (or rtx for the latest) so that you can use the iRay.
Me personally, if I had that kind of cash, I would look for a used one that some gamer already built (intel i5 or i7/ ryzen 5 or 7) and throw in 2 gtx 1080-ti cards (making sure it had 2 slots to hold 2 video cards). The two cards work together fine for rendering and your renders would go very fast.