i went $35 over your budget, however it is definitely worth it as it is a very good build, i went for the R9 280 over the 750ti as although it is a bit more expensive it is worth it, it is very good 'bang for your buck'.
PCPartPicker part list:
http://pcpartpicker.com/p/nWQnJx
Price breakdown by merchant: http://pcpartpicker.com/p/nWQnJx/by_merchant/
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($99.99 @ Newegg)
Motherboard: Gigabyte GA-970A-UD3P ATX AM3+ Motherboard ($76.98 @ Newegg)
Memory: G.Skill Value Series 8GB (2 x 4GB) DDR3-1333 Memory ($54.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($52.49 @ OutletPC)
Video Card: MSI Radeon R9 280 3GB TWIN FROZR Video Card ($179.99 @ Newegg)
Case: Rosewill Galaxy-01 ATX Mid Tower Case ($39.99 @ Amazon)
Power Supply: Corsair CX 500W 80+ Bronze Certified Semi-Modular ATX Power Supply ($44.09 @ Newegg)
Total: $535.52
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-04-22 19:54 EDT-0400