As the title says. There are many held items, team items and such that are very expensive or difficult to get ahold of. I would request blocking these items from being sold to Kecleon. It would be case-by-case for obvious reasons, but I recommend items such as the Tight Belt, Treasure Specs, Clear Rock, etc, be blocked from being sold to Kecleon by accident.
this would be a great idea or adding a “are you sure you wanna sell this?” kinda deal
How about rather making them unsellable to kecleon, add an option to “opt in” for a particular item as unsellable and have like a (y) in front of it?