In season 11 episode 14 "Top Meat and Greet," Shana and Edwina bid on a storage unit literally no one else wants. They end up paying $25 for the contents of the unit, which contains some pretty bizarre items. The duo find a creepy wind-up doll as well as an assortment of seat belts.
However, the strangest object comes when they do a bit more digging, and they stumble upon an old wooden box from World War II with what looks like Japanese inscriptions on the front. They open it up, and they're stumped at what they're looking at. It looks like the end of a samurai sword as well as tools to put everything together. Later in the episode, they bring the box to an expert who tells them the miscellaneous pieces inside the box, which includes a volcanic rock and an old set of Japanese sewing scissors, aren't worth much. However, the box itself it incredibly valuable.
The expert tells Shana and Edwina that it's a machine gun box from WWII, that was likely used by a Japanese soldier. While he says that the random katana parts inside the box aren't really worth much, he says that to the right buyer, the box itself could be worth up to $1,000. It may not have been what they were expecting, but it was a pretty sizable haul for only investing $25 in the storage unit.
