Well that sucks bad, but for $3600.00 I would expect a complete new engine. Maybe I am way off course on prices because i do alot of work myself, but that sounds VERY high for a head. I would think you could get one from someone parting out a vx for relatively cheap, like a couple hundred bucks, again maybe I am way off course.

Whats interesting to me is, what the cause could have been, I agree it is the hardest plug to get to and very easily to %^$* up, and I would say it probably was cross threaded. Its probably too late, but I would try to get him to admit whether he pulled them before you say what happened, beacuse if it were cross threaded a close examination would reveal it. However if he knows in advance, its not likely he would admit to it.

Personnaly I cant imagine changing the gasket without pulling the plugs, but I suppose technically its not a requirement to do so.

Hope that helps a bit
Keith