Maybe look at this:
PCPartPicker part list:
http://pcpartpicker.com/p/xWdvdC
Price breakdown by merchant: http://pcpartpicker.com/p/xWdvdC/by_merchant/
CPU: Intel Core i5-4690K 3.5GHz Quad-Core Processor ($239.99 @ Newegg)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($25.98 @ Newegg)
Motherboard: Gigabyte GA-Z97X-Gaming 5 ATX LGA1150 Motherboard ($144.99 @ Newegg)
Memory: Corsair Vengeance Pro 8GB (2 x 4GB) DDR3-1600 Memory ($91.99 @ Amazon)
Storage: Corsair Force LX Series 128GB 2.5" Solid State Drive ($69.67 @ NCIX US)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($49.99 @ Amazon)
Power Supply: Corsair CX 750W 80+ Bronze Certified Semi-Modular ATX Power Supply ($71.00 @ Newegg)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer ($14.99 @ Newegg)
Total: $683.60
Prices include shipping, taxes, and discounts when available
It's a pretty solid build, just add your GPUs and a case, and you're good to go!