Nikola,
This nice 1915 has been for sale in Germany for over 1 year with an asking price of 1600 Euros and has not yet sold...so that may indicate that seller's asking price is too high on that gun. I think this gun is close to the condition of your gun...
http://www.collector-arms.de/produkt_images/11000.JPG
Here is the link to the web site so you can see pricing in DE...the 1915 is down this page about 1/2 of the way :
http://www.collector-arms.de/index.php?content=kurz