For those who already have a favored grip and trigger picked out, Armalite has a LPK without the grip and trigger for $54. Saves a bit of cash for parts you have already planned on not using.
Nathan, I agree with your mindset. I built an 18" SPR-esque AR knowing full well that I could have bought a rifle length upper already assembled and would have been good to go, but where's the fun in that? I feel a bit more satisfaction knowing that I picked out the parts and that the configuration isn't as common, it really is MY rifle.
Good equipment will never be a substitute for good training.