Jim, I'm not sure what you mean about the distinct lines. From your photos, it appears the finishing marks are proper. That is the left side finishing grain is horizontal, ie, front to back, while the trigger plate finishing grain is vertical, up and down. A refinished pistol often has been over polished and the grain is not present or at least blurred. Your Luger looks proper.
It is very difficult to see some of the finish on the Luger because the photos are very dark. I can use software to lighten the photo, but then I loose definition on color. So I really can't judge percent of original finish.
I don't blame you for being careful about removing the grips. First one should have the correct screw driver. Then remove the right side grip and examine it. The right side grip is stronger than the left since it isn't cut away for the safety lever and magazine release button , in a thin section. Remove the magazine and view the left side grip through the frame. If the grips are numbered, you can usually see both grips numbers in this fashion. If they are just marked with the Waffenamt Mark, then you have to trust the examination of the right side.
Now for the holster. If Jerry does the repair on the closing strap, chances are excellent you won't be able to tell it has been repaired. It should enhance the value of the holster, if the rest of it is in good condition!!
Now for value. In all probability, you have a correct pistol. By that I mean all matching (with the exception of the grips because you don't know). You can sell the two magazines and buy a black plastic bottom fxo magazine for the money you get form the two you and maybe have a few bucks left over. The pistol doesn't appear to be the 99% finish type. If it's above 95%, you have over paid by roughly less than $200. If it's only 90%, then I would recommend you take it back. If you are in that middle fence sitting posture, it's your call!!
Good Luck!!
