find out the brand of the light..find out the brand of the skimmer..you said everything except livestock, does that include livesand and live rock? check it out see if he is giving u a COMPELTE sump..also see if the system is complete enough so that all you have to do is add water and fishys..
if the system is complete like how i stated, good MH fixture that is not old, then id give him 300-400