Head Gasket Problem, '02 Pontiac Grand Prix

I'm currently attending college in upstate New York, about 200 miles
from my home (and my regular mechanic). During the past week or two, I
would occasionally smell antifreeze after parking my car (a 2002
Pontiac Grand Prix), but I figured it could wait until Thanksgiving
break, when I could take it to my mechanic and get it taken care of.

Apparently not. I brought my car to get an oil change today, and about
30 seconds after pulling the car into the garage the mechanic came into
the waiting room holding a plastic cap in his hand and told me that he
wasn't going to change the oil because there was a problem with my head
gasket, and antifreeze was getting mixed into my oil. He recommended
that I take it to a mechanic as soon as possible and get it repaired to
prevent my motor from getting destroyed.

The problem is that I'm far from my regular mechanic and I'm pretty
uneasy about driving 200 miles home with a damaged head gasket. So I'm
curious about how much a repair is likely to cost and I'm wondering if
there's anything I should know about this kind of problem before I
start looking for a mechanic. I realize the details I've given are
kind of vague, but my knowledge of head gaskets (and engines in
general) is pretty limited. Are there any national chains that I
should look into for this kind of work, or, better yet, does anyone
have any recommendations of good mechanics in the Capital District of
New York?

Thanks,
Bill