Aluminum heads $ per HP?

Out of the box,bolted on to existing short block,with any special pieces needed to work,what is the dollar amount spent per horsepower? And lets narrow that down to rocker shaft versions with standard rocker arms,not offset. Changing springs to match cam not part of dollar amount.
Thanks! Bob P.S. don't include the blow-out sales that pop up every once in awhile, just standard Summit/Jegs/CNC performance and such.