It's OK to see how you get on with it it before plunging for a proper MAC but it's more hassle then it's worth. You have to be selective about what hardware to pick, wait for the guys that develop OSX86 releases to get to work with the update.
I have already built one and it's OK but you get so many quirks, it doesn't compare to a real Mac,
Will also be interesting to see what happens with the Psystar case, as I can see Apple implementing some nasty changes to stop it working if they lose there court case.
At the moment Apple tolerate OSX86 as it is non-commercial and they don't really publicise themselves. With Psystar going out advertising then could ruin this for everyone.