In the Place Where Great Britain Used To Be, arms collectors are largely reduced to owning legally "deactivated" firearms. The process is involved, pretty much permanently ruins the gun for any use other than as a source of spare parts, and costs around £80 (~$135) according to my pal staghounds.
While the world is unlikely to miss a few extra Mosin Nagant 91/30s or Arminius revolvers, .455 Hand Ejectors don't exactly grow on trees...
For a good look at the carnage, go to Bonham's auction site and plug "deactivated" into the search engine. (The Luger was also especially painful...)
BONUS: An entire business dedicated to selling deactivated guns! There's something immensely sad about an adult human being actually paying money for a deactivated GSG-5 .22. That's only half a step above a deactivated Red Ryder.