Most people will say if the head is coming off, you might as well get the whole head done, it couldn't hurt, and it shouldn't make it cost much more. You should be able to find a completely rebuilt head for less than $1000 and then of course you'd have to pay labor, but the head would be like new. I believe Don Swinford mentioned a place in another post.
If its just the gasket, $1200 sounds to me to be ridiculously expensive for just a gasket.
For $1200 you should be able to get the whole head done, unless your mechanic is telling you $1200 because he is going to be redoing the head, not just the gasket, in which case the price isn't bad, not great, but nbot bad.
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