Assuming you're starting from nothing (I'll mark the peripherals with an asterix * as if you already have them then the build will work out a bit cheaper)
Power Supply (should come with a power supply)
Optical Drive (DVD or Bluray)
When I get the time I'll see if I can find something reasonable to put against each category!
I think honestly, you're going to struggle to build a PC at that price point which will comfortably run the game well, especially if you need to buy a screen too!