500$ PC
Well if high-end stuff includes Fallout 4 then you'll need a bigger graphics card budget. If just GTA V and Minecraft, LoL, CS:GO, Farcry 3, etc. then a GTX 750 Ti should be fine. Just 100$. What do you think?
C'mon Mongius don't be hasty. Samuel, any chance you can higher your limit to 700$? If you can I think I have just the parts list for you.
Note 2 : these are suggestions focusing on raw gaming performance. Meaning these will result in the most FPS and the highest graphic settigns in games.