Where you buy from isn't a big isue, whoever sells the same thing cheapest is where you want to buy that item. Rarely do I suggest buying all your parts from the same place as you are losing out on savings that could make your computer more powerful.
PCPartPicker part list / Price breakdown by merchant / Benchmarks
CPU: Intel Core i7-3770 3.4GHz Quad-Core Processor ($289.99 @ Amazon)
Motherboard: Asus P8H77-V ATX LGA1155 Motherboard ($115.99 @ Newegg)
Memory: Corsair 16GB (2 x 8GB) DDR3-1600 Memory ($64.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($74.99 @ SuperBiiz)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($74.99 @ SuperBiiz)
Storage: Corsair Neutron Series 120GB 2.5" Solid State Disk ($114.99 @ Newegg)
Video Card: Sapphire Radeon HD 7970 GHz Edition 3GB Video Card ($444.98 @ Newegg)
Case: Corsair 300R ATX Mid Tower Case ($64.99 @ Newegg)
Power Supply: Antec EarthWatts Green 650W 80 PLUS Bronze Certified ATX12V Power Supply ($49.00 @ Amazon)
Optical Drive: Asus DRW-24B1ST/BLK/B/AS DVD/CD Writer ($16.99 @ Newegg)
Monitor: Asus ML228H 21.5" Monitor ($149.98 @ NCIX US)
Operating System: Microsoft Windows 8 Professional (OEM) (64-bit) ($139.99 @ Mac Mall)
Keyboard: Corsair Vengeance K60 Wired Gaming Keyboard ($68.46 @ NCIX US)
Mouse: Logitech G9x Wired Laser Mouse ($68.95 @ B&H)
Speakers: Logitech Z313 25 ($44.99)
Total: $1804.26
Total Without Case, Optical Drive, and one of the HDDS: 1,647.29
(Prices include shipping, taxes, and discounts when available.)