cooling system is a little more, you need a keyboard, mouse, monitor, electric cords,and also an AC/DC converter AC current which is used in U.S will fry every thing in your computer, so i can see around $600 to $750 depending on what you spend. i took a class in my high school to learn how to build computers, really its not all that hard. o plus you need OS software,( you could go with Linux but it not compatible with most games.) , and that it self will costs you $150 if not more
EDIT: Br0sk1 if the video card is a 1GB it will run everything and anything. you should be fine
im thinking this game will need about 500MB video card and 2.5 to 4 GB of RAM
If I need a keyboard, mouse, monitor, and surge protector, then you need controllers and a TV. Except we all already have those things, they don't count.
A "Cooling system" will come with whatever components you buy - you may need to buy your own case fans, but that's cheap, and the stock cooling will be absolutely fine for stock clocks.
A quick lookup, assuming you don't already have a windows license, you can get a copy of Win7 Home Premium for about $60.
If you want to make an omelette from scratch, you must first create the universe, and all that. You can go as deep as you want, but as far as I'm concerned, a computer is the case, and the things inside, and all of the peripherals connect through standardised interfaces for a very good reason.