So why is an hour of CD recorded music, often with new tracks you might not like, costing twice as much as the live gig?

Er.. perhaps you might listen to it more than twice. According to your argument, CDs are grossly under-priced, because you're likely to listen to them dozens, if not hundreds, of times. Compared to the cost of a live gig, they offer great value of money. Of course, listening to live and recorded music offers different experiences, but one is not necessarily inferior to the other.

I also don't understand your argument about not liking some tracks. When you go to see an artist perform live you have no idea what they're going to perform, so you have no assurance that they'll be songs you enjoy. At least with an album you can look at the track list before buying it. Besides, if an album is a new release it's probable that the artist will perform much of it during live gigs.

Except for a very few acts at the top of the tree, volume sales are difficult to achieve in the folk world. I also get the impression that folk audiences are quite hard to impress, and that it takes more than a cheap CD to win fans.