Not a pre-built (eg HP or Dell). But a BYO -
CPU: Intel Core i3-4160 3.6GHz Dual-Core Processor ($108.95 @ SuperBiiz)
Motherboard: ASRock H97 PRO4 ATX LGA1150 Motherboard ($81.89 @ OutletPC)
Memory: G.Skill Ares Series 8GB (2 x 4GB) DDR3-1600 Memory ($52.99 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($44.99 @ Amazon)
Video Card: Gigabyte Radeon R7 260X 2GB WINDFORCE Video Card ($112.98 @ Newegg)
Case: Corsair 100R ATX Mid Tower Case ($37.99 @ Micro Center)
Power Supply: Antec 450W ATX Power Supply ($32.42 @ Amazon)
Operating System: Microsoft Windows 7 Home Premium SP1 OEM (64-bit) ($85.75 @ OutletPC)
Total: $557.96