You only need an aftermarket cooler if you want to overclock. If not, the stock cooler will be fine.
So are you actually gonna spend $700 or are you going to keep it at $600?
PCPartPicker part list:
http://pcpartpicker.com/p/3LM6f
Price breakdown by merchant: http://pcpartpicker.com/p/3LM6f/by_merchant/
Benchmarks: http://pcpartpicker.com/p/3LM6f/benchmarks/
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($109.99 @ NCIX US)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($29.94 @ OutletPC)
Motherboard: Asus M5A97 LE R2.0 ATX AM3+ Motherboard ($69.99 @ Newegg)
Memory: A-Data XPG V1.0 8GB (2 x 4GB) DDR3-1600 Memory ($63.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($56.98 @ OutletPC)
Video Card: XFX Radeon R9 270X 2GB Double Dissipation Video Card ($182.94 @ Newegg)
Case: Corsair 500R White ATX Mid Tower Case ($59.99 @ Newegg)
Power Supply: EVGA 500W 80+ Bronze Certified ATX Power Supply ($32.99 @ NCIX US)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($89.98 @ OutletPC)
Total: $696.79
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-05-17 14:09 EDT-0400)