I guess what you really need to do is ask yourself what you mean by expensive? I know that expensive for me may mean something completely different for someone else. Basically I need more information to help. Are we talking a $600 computer that will play newly released FPSs at max level? Or are we talking a $1500 computer? I really don't think designing and building a computer is all that hard, just take your time and research each component thoroughly. It's a great way to learn and there are many forums available that will help you check the compatibility of your components.