[Sorpanino]

Build something with like a fx6300, gtx 760 for gpu, and like 16gb of vengance if you do a lot of rendering

 

[fuego]

The budget is more than enough for a decent spec. Not only 12GB but you can even get 16GB DDR3 for less than 1000 bucks. Go to Google and search for Lenovo TS140 or X315, these are 2 of the most high powered desktops available nowadays. Or check out more options at PC Mag or Consumer Top
 
You can even order it with an OS of your choice if you don't like Windows 8 or 10.