Hello,
I can give you a couple of places for information.
1. If you do a search on this forum, you will see several long discussions about this subject.
2. If you go
http://www.lugerforum.com/45Luger.html which is here on the forum, you can read this article.
The short of it is, there is a 45 ACP in a private collection and there is a 45 ACP at the Norton Gallery in Shreveport, LA.
The million dollar is a guess, because the last time one was sold was for around a purported 850,000 dollars.
Ed