In my opinion the main problem is that the ones offered are mainly Herder and Hammesfahr SS full Röhm's: these are 99% of the time standard early M33 SS with the inscription added postwar.
After adding the inscription, the blade is artificially aged, often by applying unusual rust spots, so that it appears that the inscription was there (under the newly added spots) all the time.
The Eickhorn, Klaas and Bökers, which used a smaller specific logo on their Röhms, are almost never offered for sale. And when the are, astronomical prices are asked, like with the Eickhorn in the topic...
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