Building an imac (or better)

ok so, i bought an imac, 10 days ago, and today i took it back, the screen was killing me, i have horrible eye strain and the brightness on the glossy screens is stupid

to get the colour definition ineed to work with i had to have it up to fully brightness, suffering from albinism i have a hyper sensitive retina and simply cannot cope with the extended exposure not to mention a lack of sharpening in the os menues causing me to squint (which combined with the small font size is just horrible)

however, despite this, i love the os, the first tiem i have ever had one, and im hooked

unfortunately i cant get a system anything like equivelant from mac that doesnt have the glossy screen, so im left with no choice but to build one,

so where do i start?

what do i need to know?
is there certain things that will and wont work?
and how much am i looking at?
(and also anyway of reducing the size of the tower i will need)