Guns and gun part movement across the US border is currently controlled by the State Department via International Traffic in Arms Regulations (ITAR). So... You could ostensibly find such a feed mech in Germany at a "reasonable" price. It's getting it here that becomes the metric and imperial pain in the glutes. You have to comply with German export requirements and then you have to comply with US import requirements. This usually entails enlisting a licensed importer or broker who is already familiar with the circus. That has a price (usually significant). Spread that price across 100 units and it is a bit bearable. Just one? Not so much. Which is why they remain so expensive on GB.