MiNr 15 and 16 are actually really common, and can be had relatively cheap compared to other forgeries. Unfortunately, most of the easy sources are German, so there's a language barrier that you'd have to navigate.
There are several on the German eBay
There are also some available from German auctionhouses on Philasearch
, including several available at after auction sales.
Also, your copy of the Hitler Skull forgery is fake. The legitimate ones are perforated. They're also relatively cheap, and can often be purchased alongside 15 & 16