I quite agree. Obviously a nut can do little for the tone of anything other than open strings, where you score with a bone, Graphtech or Tusk nut is they are both harder and slippier than plastic, this means the strings are less likely to hang up in the slot when bending or using the trem.
Going back to the original question, if you can squeeze the money out of your budget for a fret dress and decent setup, that would make a lot of difference to the feel and playability of the guitar.