Try -
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($106.02 @ Amazon)
Motherboard: Gigabyte GA-970A-D3P ATX AM3+/AM3 Motherboard ($69.99 @ Newegg)
Memory: G.Skill Ares Series 8GB (2 x 4GB) DDR3-1600 Memory ($79.99 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($53.98 @ OutletPC)
Video Card: Gigabyte Radeon R7 260X 2GB Video Card ($142.98 @ SuperBiiz)
Case: Corsair 200R ATX Mid Tower Case ($49.99 @ Micro Center)
Power Supply: Antec High Current Gamer 520W 80+ Bronze Certified Semi-Modular ATX Power Supply ($77.98 @ OutletPC)
Total: $580.93
Performance: http://extremespec.net/gigabyte-radeon-r7-260x-gv-r726xwf2-2gd-review-design-testing-performance/