Damn, how could I forget the psu :/ hertz is right about the ram.
PCPartPicker part list:
http://pcpartpicker.com/p/qLjtsY
Price breakdown by merchant: http://pcpartpicker.com/p/qLjtsY/by_merchant/
CPU: Intel Core i3-4130 3.4GHz Dual-Core Processor ($105.75 @ OutletPC)
Motherboard: Gigabyte GA-B85M-DS3H Micro ATX LGA1150 Motherboard ($47.98 @ OutletPC)
Memory: G.Skill NS Series 8GB (2 x 4GB) DDR3-1333 Memory ($63.98 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($48.88 @ OutletPC)
Video Card: XFX Radeon R9 280 3GB Double Dissipation Video Card ($152.99 @ NCIX US)
Case: Corsair SPEC-01 RED ATX Mid Tower Case ($41.20 @ Amazon)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply ($49.99 @ NCIX US)
Total: $510.77
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-01-30 11:09 EST-0500
Spend the 10 extra bucks, it's really worth it. I used to run titanfall on ultra with an i5 2300 and a gtx 660. Obviously, not on 60fps. But playable imo.