For that price range I have to recommend amd, they have similar and better performance than their nvidia counterparts for a fraction of the cost. Some good ones are the r9 270x @ $180, r9 270 @ $160, r7 265 @ $150. I would lean towards the r9's because they use the more current Hawaii architecture and will be more future-proof. If you could boost that budget to ~600 that would be optimal, because then everything else wouldn't have to be really cheap. This >
http://pcpartpicker.com/p/Y6LMMp is a good build for about that range. It could be cheaper with 4 gb of ram, cheaper mobo (dont reccomend downgrading this), no cpu cooler, or going down a grade on the graphics card. Happy Building
- Major_Headahce