Hi Skandi,
Sorry for the late reply. I was looking through an old stack of papers today and ran across a pamplet from the forening Frøsamlerne , which means "the seed savers association". I had visited their booth at a
permaculture festival back in 2014 and on the cover of the pamplet I had written the word "Yacon". They had a table at their booth with various interesting produce, one of which was yacon. I was and still am interested in yacon but haven't yet taken the effort to get it yet.
I just had a quick look at the frøsamlernes website and see that they had two members offering yacon in their 2017 list.
http://www.froesamlerne.dk/sites/default/files/%20%20Fr%C3%B8listen%202017%2C%20uden%20udbydere.pdf
There's also an article on yacon in the book "Permakulturhaven" and on the havenyt.dk site is some info and nice photos.
I'd be interested to hear if you find a source. I'm on the island Als so quite a ways South from you (I'm at 55 deg N).
Regards,
David