The Hitler Walther shown on The History of the Gun, was a PP model, NOT a PPK. Next time it's on, check the length of the slide.
It was made by Walther for presentation to Hitler, and this is verified by the Walther factory both by the serial number and the very special work done to it. It was heavily engraved, gold plated, ivory gripped, and had "AH" initials inlaid into the grip.
There is a very tiny amount of blood of Hitler's type on the gun. Nobody has ever suggested that this was the gun he used to shoot himself.
There is some discussion that this was the gun his niece shot herself with, (or was shot with), and that her blood type may have been the same as Uncle Hitler.
It was recovered from his apartment in NUREMBERG, not Berlin, and was recovered by US Army personnel.
Good accounts of Hitlers taste in guns has him actually carrying rather plain pistols, without all the gold, engraving, and ivory.
This fit his image of himself as a Soldier, and soldiers didn't carry "pimp" guns. Many fancy guns were presented to him, but the people around him said he usually had fairly plain guns as actual carry pieces.
As an example, when he personally arrested Ernst Roehm (sp?) the SS guards he was with were surprised to see him carrying a plain, no frills, unadorned Luger.
As to what happened to the Hitler suicide gun, either it was the ultimate Nazi icon and was hidden away by die-hard nazis, or it was such a plain, unremarkable Walther PP, that whoever has it probably doesn't suspect what it is. If the did use a plain soldiers pistol, there would be nothing to distinguish it from millions of other PP pistols.
The famous hammerless Walther P-38 prototypes are well known and have all been pictured in books and described pretty well. These were seized by US and possible British troops. There were only a very few made as experimental models, and Hitler never even saw one as far as is know, much less had possession.
As for fake guns, a few years ago I seem to remember a story about somebody getting into trouble for attempting to scam Southaby's with a fake Hitler suicide pistol.
The best fake gun producer may have been Bat Masterson. When he was living in New York and working as a sports writer, he would go down to a pawn shop and buy a load of cheap old revolvers. When people asked him about having one of his famous Kansas guns, he'd give them one of the junkers, along with stories about it's usefulness in his lawman days.
In the 1880's he ordered two plain Colt 4 3/4" rubber gripped sixguns from Colt, and these were his actual lawman guns. Only ONE is known, the other is still out there somewhere.