..........
Michael's post is pretty much on the money; just to be clear, regarding one of my point's Michael's fairly picked up on, there were indeed French built examples with the Argus engine, but my comment earlier was that the
prime version in collectability is the German built examples with the original German engine; every other later version is a step away from that in status and value, and, like the example that started the thread is often oversold in a try-hard manner as a result. Certainly French production of both the Storch and 108 had German original material incorporated; but in survivors that
potential element is emphasised beyond all likelihood in many cases, given the greater value and cachet of the German stuff.
bdk's right that there are fewer Bf 108s / Nords either active or under restoration that you'd think considering the history of the type and the aircraft's performance. Most are, of course Nords of various flavours, and the issue remains that the engine options seem to remain a deterrent. Personally I'm no fan of shoving modern American engines in them, but they're not my aircraft.
French built Storche had a number of engines fitted after the Argus availability ran out; 233 hp Renault 6Q, 230 hp Salmson 9ab, the mentioned 304 hp Jacobs R-755-A and a 235 hp Lycoming.
More Storch gen available on the interweb and in:
http://mmpbooks.biz/mmp/books.php?book_id=166 
It was fun to edit, and add a few cherries, such as some of the allied examples to this.
Regards,
@JDK: I did not want nor did I intentionally criticise your post, I just wanted to state that during German rule Nord used the Argus engine. The remark on use of previous produced airframes or parts was meant not to "Germanize" any paticular plane or Nord´s in general, just to show how few (possible "original Bf 108 parts") were used on Nord´s post war production. And no, it should have no influence on the value of the plane. But the design in itself was a very progressive one for the early 1930´ies. And of course you are right in everything you posted. (I learned today, they used the Renault 6Q on the Storch as well, maybe I should get that book too. The more you believe to know, the more you find out you still have to learn.