Depending on the wattage and quality of your power supply, you have a plethora of options. Following suggestions listed from least in performance to greatest.
GTX 750Ti Superclocked 2GB - $129.99
Economical & budgeted. It's what I'd consider tier 2 of the entry level gaming GPU's. Much better than a GT 610
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R7-260X 2GB - $138.99
Also tier 2 for entry level cards, in my opinion. A hotter running card than the 750Ti, but it edges out a win in performance overall. Well priced
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R9-270X 2GB - $170.00 With Promo Code PCAMDRDN15
Upping the performance level quite a bit. Able to play most titles at 1080p with very favorable frame rates. Also priced quite well for what you're getting in comparison to other similarly priced hardware.
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GTX 760 2GB - $188.40 With Promo Code HSYGSKS9
This particular third party port of this card is priced decently per it's performance, mainly cause newegg is doing a good promotion. Otherwise these cards are usually overpriced. Excellent performance, with it clearly outclassing the 270X
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R9-280 3GB - $181.10 With Promo Code PCAMDRDN9
This is your value if you want the utmost your budget allows for. A better option than the GTX 760 for several reasons, but my favorite being the progressive addition of 3GB VRAM making crossfire/multi-monitor options more viable in the future.