RE: Mountain Goat Hunting
Ballpark, $6000-10,000. Depending on the guide/area/number of days you pick. Best state would be Alaska if you want to stay in the us. I would opt of British Columbia myself. Lower 48 I would look into Idaho or Montana up near the BC line.
As far as the trophy question. I think that whomever told you that it was undesireable, is an idiot. In my book it is one of the most desireable trophies to be had. Goats and sheep are the pinnacle in my estimation. No"hunter" that has seen a lifesize mount of a mountain goat would call it anything but awesome. Goat and sheep hunting tests a hunters "metal". They are earned not killed.