Build. Companies rip them shit off of you.
1) Its a great learning experience, can get frustrating, but you'll get over it. Just have someone help you. Maybe a geek in the family.
2) They just run way better for way cheaper. Givin you do it right.
I built my own pc 2 years ago, it has a great video card, 8gb DDR3 RAM, a intel quad core processor.. And its really really good. I hardly spent any money. If I were to buy a pc like this back then... Jesus man my wallet would turn into a black hole.