The biggest question should be "do you have a microcenter near you" , resolution and settings, thunderbolt needed, overclocking?, and "what games"? You can get a i5-3570k+ Z77 motherboard like the Z77x-UD5H for $300 or less but the caliber of the motherboard will be different if you don't have a Microcenter near you.
$220 i5-3570k ($150-160 at Microcenter)
$180 z77 motherboard like the GA-Z77x-up5 TH, GA-Z77x-ud5h, or P8Z77-v Pro ($180-200) , if overclocking
* $100-120 z77 motherboard like the GA-Z77x-D3H if low 10-15% OC like 4GHz (note the UD3h is a different model with $150 MSRP) .. it's better than the Asus P8Z77-V LK and Asrock extreme4 is analog VRM which provides less stable power
$280ish HD 7950 of choice (MSI, gigabyte, Sapphire,HIS, Asus etc) or $250ish Sapphire HD 7870 XT tahiti LE to save some money due to not living near microcenter
$40ish Corsair Vengeance low profile RAM or Gskill ripjaws
$100ish for 64 /80/120/128GB SSD like Samsung 840 Pro, Samsung 830, Intel 520,etc.
$50ish for a HDD to dump stuff on
$20ish for a Coolermaster 212 Evo or 212+ , or other aftermarket cooler
$80ish Decent 550 or 650W PSU unless you plan on crossfire such as Rosewill HIVE 550W modular, Rosewill Capstone CAPSTONE-650-M, Seasonic G Series SSR-550RM , SeaSonic M12II 650 , CORSAIR Professional Series HX650 , Antec HCG M Series HCG-620M 620W...
$70-100ish Decent case of choice such as Fractal Define R4, NZXT Phantom 410
If you're playing RTS or Starcraft II, then you don't need any more than a HD 7850 or GTX 660 to get 60FPS. For First Person Shooters (Battlefield, Crysis 2), Action RPGs like Elder Scrolls Skyrim, etc. you will need more like a HD 7870 because even the GTX 560ti will have some issues on higher settings.
P.S. The Corsair 200R is pretty bad for $50 when the 400R/500R are on sale for $70ish-80ish. The only time it's a decent case is when it drops to $30-40ish because then you can get more fans & a filter for the bottom of the case.
Edited by AlphaC - 2/17/13 at 2:28pm