I would say it is a historical piece & even a rare piece for the Simson/Waffa/BSW/Gustloff-Werke evolution. Rare pieces aren't necessarily valued highly nor does history add much in the eyes of most potential purchasers. But considering the above, along with replacement value, insurance, etc. I would hazard a guess a range of $1800 U.S. of A. to $2200. But putting it on an auction site or out for bid is the only true way to determine a realized value.
Then you get a bit of a dose of reality w/ Rocketman's value calculus:
"I value vintage guns reasonably accurately by combining Original Quality grade (OQ), Brand Value level (BV), and Current Condition level (CC). So, I'll assume this was between a second and third grade OQ gun (OQ6 to OQ7); say, 1/3 good engraving coverage, good figured wood, and good fit and finish. The brand value level for BSW is level four or BV4 (lessor known Continental makers, often associated with modest quality guns). Assume the Current Condition is between CC3 (significant use) and CC4 (heavy use, but no abuse). BV4-OQ6-CC3 = $1160, BV4-OQ6-CC4 = $883, BV4-OQ7-CC3 = $810, and BV4-OQ7-CC4 = $616. See if you can fit the gun as you see/remember it into that matrix......"http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=389449&page=all