Marcel,
I have been on the look-out for a Reichs cockade and recently purchased an original ( I hope; not received yet) for $62.50. I was happy to have the opportunity to find and purchase for my M15; even consider myself somewhato "lucky" at this point. Time will tell.
One of the realities of collecting an item like a cockades, buttons, tinnies or anything or part of something that was originally stamped is that many of those original punch and die sets are still extant. The knowledge to very closely duplicate the patina, whether rust, worn or chipped paint, etc. is also available. Even if the original tooling is not available there are several methods to reproduce the tooling or part using an original as the model especially with CAD and CAM systems. If there's money to be made rest assured repros and fakes will be produced.
You're correct one can easily assemble a parts helmet (or other) valued higher than the market will bear at the moment. But you can always retionalize that you didn't pay too much, you just bought too early.
Take care,
John