PCPartPicker part list:
http://pcpartpicker.com/p/JhJPQ7
Price breakdown by merchant: http://pcpartpicker.com/p/JhJPQ7/by_merchant/
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($118.98 @ OutletPC)
Motherboard: MSI 970A-G43 ATX AM3+ Motherboard ($69.98 @ OutletPC)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory ($74.70 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($54.98 @ OutletPC)
Video Card: XFX Radeon R9 280 3GB Black Edition Double Dissipation Video Card ($243.98 @ SuperBiiz)
Case: Corsair 200R ATX Mid Tower Case ($49.99 @ TigerDirect)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply ($34.99 @ Newegg)
Optical Drive: Asus DRW-24B1ST/BLK/B/AS DVD/CD Writer ($19.98 @ OutletPC)
Operating System: Microsoft Windows 8.1 (OEM) (64-bit) ($89.98 @ OutletPC)
Total: $757.56
Prices include shipping, taxes, and discounts when available
Here is a build for around $750 and will play nearly all games on ultra