Back in February I got
I7 2600k unlocked
16gb 1866mhz DDR 3 ram
Asus p67 sabertooth mobo.
Nzxt phantom computer case
Coolmaster v6 CPU fan
Costed me about 1 grand
Recycled my old powersupply, gpu, and hdd
Then I got a 27" led Samsung slim 1080p hd monitor for 179+tax
And for hardware I got a G300 headset $150
G510 keyboard $120
And a $47 Logitech gaming mouse don't remember what G number it was
This will give you an idea as to what you can get for your budget won't be to extream like my setup but
Look for something with atleast an i5, gtx 560 or better, and minimum 8gb of 1600mhz ddr3 ram.
I would suggest looking at other places then bestbuy tigerdirect has great computer deals