[agtw31]

color?options?condition?

answer these questions.

thats a rare w31.
if the car has the original block with the w31 balancer,and
he has proof(broadcast sheet,build sheet) that its a true w31,then thats a good start.not keeping the original intake and original heads is an expensive mistake.
if he has no documentation showing the w31 option,he's hit real hard,price wise.

you need to give more info on the car to get an accurate idea of a price..

also,dont go by the ones you see on ebay.