Great thread.....! RK - BTW - if you keep on making posts/replies like that, I'll have no choice but to make you a Moderator or Administrator..
I want to follow-up on something Tom mentioned - dealer vs. collector. My suggestion is that if you can find a collector in your area, spend some time with them and ask to see some of their pieces. There is no substitute to "hands-on knowledge". Sure, pictures are a terrific learning tool, as well as forums such as these - but to actually see, in person - some of the nuances of each variation, will assist in knowing what is "proper" for each variation itself...
As well - your local collector(s) often trade-up and/or sell pieces off. In developing a working association with a local collector, you may find that you have the opportunity to acquire a Luger that you are familiar with the background. Dealers, because they buy/sell in quantity, usually don't have the time/resources to track the background of each piece in their inventory...
Finally - have a plan or a blueprint for your collection. Seeing, firsthand - each variation, period piece and various Luger models - will help to develop that plan. For example - are WW2 pieces more interesting, or Imperial pieces, or early squeeze gripped models? Seeing these variations - and knowing the unique characteristics of each - will lessen the potential for your acquiring something that isn't "quite right"....
Anyway - great questions, replies and comments....!