Thanks a lot for your replies! So I think we settled the price the previous owner paid for it :-)
But the puzzle of the reference (similar to) D.B.M 2495 still remains :-(
My wild guess
DBM = Deutsches Bundes Mark = German Federal Marks (or possibly German bank marks) = Deutsche Marks. ähnlich would have to mean "equivalent to" rather than "like", which sounds possible though my German isn't good enough to be making such guesses. But if it was, then just track back to when CHF 900 = DM 2495 and you've got the purchase date.
Andreas and fellow Germans, could this make sense?