GCK,
It's just one of those collecting things that happen. Not long ago at all they were thought of as any other import marked gun and only had a small following. I think some of this is fueled by the CMPhype and sometimes it doesn't reflect true long term market value but who knows about collecting.
The one difference I appreciate about them is the Germanguns have generally been taken care of far better that the imported Korean, etc.
Personally I don't think the difference between a good rebuild of the same quality and a Bavarian marked carbine should be more than $100 or so. JMO