All I could do. I couldn't bump in a 660ti or a 660 I just made it into a 7850. It's just 3 bucks over your budget:
PCPartPicker part list:
http://pcpartpicker.com/p/2NtqB
Price breakdown by merchant: http://pcpartpicker.com/p/2NtqB/by_merchant/
Benchmarks: http://pcpartpicker.com/p/2NtqB/benchmarks/
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($119.99 @ Newegg)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($29.98 @ OutletPC)
Motherboard: ASRock 970 Extreme3 R2.0 ATX AM3+ Motherboard ($79.99 @ Newegg)
Memory: A-Data XPG V1.0 8GB (2 x 4GB) DDR3-1600 Memory ($69.99 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($64.99 @ Newegg)
Video Card: PowerColor Radeon HD 7850 2GB Video Card ($149.99 @ Newegg)
Case: NZXT Source 210 Elite (Black) ATX Mid Tower Case ($42.98 @ Best Buy)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply ($39.99 @ Microcenter)
Optical Drive: LG GH24NSB0 DVD/CD Writer ($15.99 @ Microcenter)
Total: $603.89
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-02-04 21:48 EST-0500)