The best budget CPU you can get currently would be a "Intel Core i7-4770K Haswell 3.5GHz LGA 1150" for roughly $340

The best budget GPU you can get currently would be a "GeForce GTX 660" for roughly $200

That puts you at roughly at $540/800 of your budget... You may want to think about upping that budget to around $900ish to comfortably get everything else required.