Marco,
1. You might consider buying this book before considering an HK Luger purchase. Especially since HK Lugers are being made as forgeries out of other DWM Lugers.
http://www.simpsonltd.com/product_in...oducts_id=2664
To find this book for sale in Italia, you might search with this ISBN Number :
0-87833-314-2
2. In my opinion, I think an HK Luger is a better investment as only 13,000 or so HK Lugers were made and not all 13,000 survived the war. Compare that to hundreds of thousands of Lugers made by Mauser.