for anyone who's similarly into marked pre-owned cartridges, you may want to check out Famicassearch: https://bonusstage.net/famicassearch/index.php 🇯🇵
This is a non-profit collection/database maintained by Junji Seki, president of Happymeal Inc. (a prolific galakei dev that more recently began producing FC-style ADV games in collaboration with ADV veterans), with the purpose of reuniting people with their old cartridge—anyone who happens across their old cartridge can apply to get it back, with some very lenient conditions: you have to buy it (but you set your own price), you have to be willing to let Seki deliver it personally, and you have to be willing to let him share your story online.
The search options are quite granular and he does keep stock of English/overseas games as well as Japanese ones, so who knows, maybe that's your copy of Timon & Pumbaa's Jungle Games he's sitting on...?
https://www.buzzfeed.com/jp/ryosukekamba/knight 🇯🇵
Here's a feature on president Seki returning an old King's Knight Famicom cart to its previous owner after 30+ years... dude presents as an unassuming nerd, waxing about the memories of his old game, until they hit you with the pic of him in shironuri vkei paint pimping his band's next gig:
