What is the price range for a 1905 Ruger 32 automatic taken off a German officer?

Are you sure its a Ruger? Ruger firearms is an American Co. started in the 1960s. If its a Luger pistol the value could be quite high. Some Lugers bring 5 figures or more at auction. Lugers appeal to gun & militaria collectors so I would recomend have it appraised by more than one competent source. If you search the net you should be able to find a Luger forum where you can post pics to get a ballpark figure.