First, are you happy with your Luger, K? That's what's really important. Sometimes we go with our heart instead of our head. And that's not all bad, if you like your byf and the way it looks.
And are you going to use it as a shooter, not as an investment for collecting? It would be a fairly expensive shooter but nice looking so it comes down to how you value it. I've got a regular salt blued 41 byf and love it but fear to shoot it since it will reduce the value. (So is that so smart either!
) My shooter is a mixed parts P.08 that isn't very pretty, yours should be pretty and attract attention on the range.
Also does it happen to have the black bakelite grips? If so and they're in good shape they can be worth $250+ by themselves. (Crossed my mind since black grips would look good with nickel so hoping that's what you have.)
Not trying to sway you either way, it's up to you whether you got a good deal. At least you talked him down $500. Definitely post pictures!