How much is a Waffenfabrik mauser Oberndorf A Neckar 422435?
I am sorry, but it is not possible to tell much in terms of value from a serial number.
I am not even sure if what you have is a pistol or a rifle. I recommend you take some pictures of your firearm and post them here. Use natural, indirect light (shade on sunny day) and use your camera's macro function for close ups of serial numbers and markings.
If it is a pocket model pistol in 7.65 mm, in very good to excellent condition fall in the value range of $200-400.If it is a pocket model pistol in 6.35 mm, in very good to excellent condition fall in the value range of $600-800. If this information was helpful please rate by clicking on the thumbs up icon. Regards, - B.Mason