You don't need Z77 mobo if your not overclocking. A B75 mobo will do. I also would stay away from msi motherboards. Don't get a Hitachi deathstar. Get a good seagate or western digital hard drive. That psu... I would recommend a Corsair or Seasonic. And unless you are doing serious video editing, you don't need 16 gigs of ram. Gaming? I'd get 8 gigs. Normal use? 4 gigs.
What Cheesy said. Don't get Nvidia right now as AMD is owning in the GPU department. You also get Far Cry 3 for free when you buy the 7870. Lastly, if you really want it to be cheaper then get a 7850. The cheapest one would be the PowerColor brand of 7850.