If I have that opportunity there would be 3 weapons I would acquire for sure.
First one is Webley-Fosbery automatic revolver due to its rarity and unique recoil system
Second one is Luger (Parabellum) P08 due to its rich history, the fact that it is the first gun with which the modern 9x19mm parabellum caliber was used and the fact that it is the most recognizable design using the Borchardt mechanism
Third one would be a early percussion rifle solution which was very rare and not popular and of which I forgot the name. The interesting part is a cylinder on the side of the rifle which is rotating. The one side of the cylinder is reserved for percussion cap and the other side have an opening for the gun powder. You first rotate the opening upwards and put gun powder in that cylinder (which is also connected to the chamber), then close and rotate the cylinder upside down so the percussion cap comes on top. When you pull the trigger a cock strike the percussion cap which explodes, lights the powder in the cylinder which creates a chain reaction and lights the powder in the chamber. A very interesting, early percussion and rare system.