I don't know where u're from, so I'll just assume u're from USA, so this should work.
CPU: Intel Core i5-4570 3.2GHz Quad Core processor - around $200/$230
Motherboard: Gigabyte GA-H81M-S2H (or any GA-H81...) - around $40/$70
RAM: Get 8gb (2 rams, 4gb each) anything u can get will be usefull, prices are around $10/30$ but u may wanna buy something good like THIS
Hard Drive: The cheapest option would be a Barracuda Seagate 1Tb 7200 rpm, fairly common and something like $50. The best option would be buying that one for storage and a solid state drive for the OS (120gb it's around $50, 240gb around $100).
Video Card: GeForce GTX 770 2GB (or 4gb if u wanna play games like bf4 on ultra, there's like $50 difference between 2gb and 4gb). Also if u wanna get it cheap look for EVGA brand seller but I would avoid that like plague, instead look for MSI, it'll be around $200
Power Supply: Any 620W or 650W ATX - around $50/$100. If u can find SeaSonic power supplies u won't regret it, those are cheap and incredibly durable.
Case: Anything u like, but don't buy things under $100, they're usually recycled garbage.
OS: Windows 7 - 8.1? dunno really, that's up to you.