The NanoPi are available directly from the friendlyarm.com site. Just Add-to-cart and then checkout.
They are delivered pretty quickly from China. Although if you want to order a bunch of them you might get some ridiculous shipping quotes.
I think there is a distributor in Germany - but I'm not sure they keep too many in stock. Maybe someone is interested to distribute them in Europe?
About the offer for beta testing from earlier - I'll definitely keep you in the loop.