PCPartPicker part list:
http://pcpartpicker.com/p/4Fr3gs
Price breakdown by merchant: http://pcpartpicker.com/p/4Fr3gs/by_merchant/
CPU: Intel Core i5-4690K 3.5GHz Quad-Core Processor ($229.98 @ OutletPC)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($24.99 @ Newegg)
Motherboard: Asus Maximus VI Hero ATX LGA1150 Motherboard ($168.98 @ SuperBiiz)
Memory: G.Skill Sniper Series 16GB (2 x 8GB) DDR3-1866 Memory ($164.99 @ Newegg)
Storage: Samsung 840 Pro Series 128GB 2.5" Solid State Drive ($117.25 @ Amazon)
Storage: Western Digital BLACK SERIES 2TB 3.5" 7200RPM Internal Hard Drive ($136.00 @ Amazon)
Video Card: MSI GeForce GTX 780 Ti 3GB TWIN FROZR Video Card ($599.99 @ Newegg)
Power Supply: EVGA 850W 80+ Gold Certified Fully-Modular ATX Power Supply ($109.99 @ NCIX US)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer ($14.98 @ OutletPC)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($89.98 @ OutletPC)
Wireless Network Adapter: Asus PCE-N10 802.11b/g/n PCI-Express x1 Wi-Fi Adapter ($11.99 @ Newegg)
Total: $1669.12
Prices include shipping, taxes, and discounts when available
I left out a bit of money for the case, As its a personal thing but have a look at the Corsair Cases or the NZXT Phantom Cases.
This will way out-perform the build Blue_Smoke posted once you Sli it, there is no point in buying 2 lower end cards because to upgrade you have too sell both and get a new card.
Always get 1 better card for better upgradeability at around the same performance.
2xR9 280s won't be that different.