Well if you are not looking into gaming the You will want to focus on the Quattro Cards from Nvidia
At the End of the Day the Heaviest Load will be when you render you images or Scenes...
You can use an i5 CPU but even and entry level i7 will be a better investment...
So build a decent machine with 16gigs mem(8gig minimum), a top line i5, entry level i7 CPU, the motherboard and Harddisks etc are all at your discretion
The Part that matters the Most is the Quattro Card... if thats not an option just get a mid to high range gaming graphics card preferably a x70 series or higher like 770 or 970 etc or higher like a 980 or titan
the gaming cards will not achieve the Capabilities of the Quattro cards but its way more than having a baseline graphics card...
At the end of the day consider all the options line them up and then based on how much smack your wallet is prepared to talk you buy what you can afford... CPU and GPU Graphics Card will take the bulk of the Budget... the rest is at your discretion
Also a Solid State HD will improve performance as well but that is again at your descretion to buy.
You don't need a Quadro. If you're going to be using it on a daily basis then get lots of memory, an SSD and like Xenit said an entry level i7 at least
But if you're just mucking around with it, then get an i5 with less memory and a normal hdd.