Decent gaming PC with a budget of $400 -$500

Hi all, I want to get a decent gaming PC for around $440 - $500, can anyone give me any suggestions on any pre built ones at this price that could run a game as recent as The Witcher 3 (I am using The Witcher 3 as an example, I don't really care to play it.), or parts to build one for that price that can run it. (Note: I don't mind playing at the lowest settings).

The only prebuilt I would ever recommend is a Alienware alpha I3/750ti windows variant for under $450 to $400.. That can run games like Witcher 3 at over 30fps at medium settings at 1080p.. As for building one, I would hold off at that price range until you amass more like $800..

What components do you have already (case, keyboard, mouse, windows)? I have built a gaming PC once for that range, but it was pretty low-end.

@thealbinoquincy: moved to Hardware forum