I bought 2 sets of the bare, Chinese (Speedmaster formally pro comp) aluminum cylinder heads-for less expensive than half price of new heads assembled. $3XX something a piece.
I got valve jobs, valves, springs, ?seats, retainers, valve seals, guides checked for $500 something bucks (less than $550 I think) installed.
I am unpacking from my retirement move and working hap hazzardly now-no assembly as of yet.