I own a k31. It was my first C&R. I love it. I have no problem saying it is the most accurate, easiest to operate, best finished rifle I own(except for the stock which has more character than any rifle I own). The recoil is supremely soft. The straight pull bolt is like briefs lined with rabbits fur.
The ammo is expensive. There are no more in Swiss warehouses. Parts are going to start drying up. I don't shoot mine very much at all. I mostly let people take a few shots with it.
Ammo is a little less than $.50, if the gun goes down and you may be looking at buying an entire new rifle for parts. I doubt this would be a problem, but I would hate to read a post about how your last great rifle doesn't work and you had to take up fishing.
I don't think the $100 compares to the difference in ammo cost. If it was just $100 I would definitely say the k31.