These are a few that I found on a quick search of the interweb. The complexity of the Luger body and all the different levels must make the engraving process so much more difficult. The guns are nearly a work of art from the factory. Other handguns like 1911's, revolvers would give a much flatter and easier to work with canvas.
I would likely not own any of these. I love the over the top opulence.