I did one in New Zealand, to Mt Earslaw Burn...It was amazing. The Burn was carved by run off from Earnslaw glacier and is a spectacular place to see. The only people who can fly in are the people who flew us in...So it's always empty. So stunning.
Here's a few pics I took.
We paid $1000NZD per person for a 90 minute trip. ($668USD in today's rate). It was a lot of money for 90 minutes but one of the most amazing things we have done. We would do the same in Norway.
place looks amazing. down side is the price, but to be able to be in this kind of crazy place, first see it from the sky and than being on the ground and have it just for yourself is kinda priceless.
We wondered about the price, the 90 minute flight was more than our airfare from Australia to New Zealand, and if we should do it...But like you said, once in life time. It is a wondrous place and yes, the money we spent bought a priceless experience. We would do it again, and if we get to Norway we'll do it there too.