Hi Michi,
I have not been here very long, but I can tell you that this forum is the right place to be for any questions and advice you have about Luger pistols. Reading the FAQ's (Frequently Asked Questions) are a great source to start, as well as going through the many threads in this forum. Acquiring a reliable shooter is a good way to start a collection, as it gives you the opportunity to shoot it without worrying about breaking a numbered part. AND... getting a real feel and appreciation for the gun in operation is a great way to understand why this gun has such a remarkable history. Of course the price goes down as well
Good collector pieces can start at around €1500 and they go up from there.
Looking forward to hearing what happens .... take your time....
By the way, your English is very good. (I am an English instructor.)