Aren't we supposed to have access to /worth or /price in combination with /sell So that we are not guessing item prices. Not everything can be seen within /shop
EDIT: The command supposedly exists, it's just permission locked. It's a lot easier than searching manually. Especially if you are selling multiple items.
Pretty sure all items that can be bought from/sold to the server are in /shop and prices are not consistent. At /warp shop you usually get more for selling them.
I was afraid to try with some items, because I missed them at the shop, and didn't know what would happen. I know that now. But even when trying to pin an example, I failed twice. Went to the wrong category. A command like worth would make it a lot easier. Especially if you are doing multiple items at the same time. It's obviously therre, because typing it says not enough permissions. And an unknown command would say just that, unknown command.
It doesn't exist since the existing /worth command is neither bound to the /warp shop prices nor to the /shop prices which is why no one can access it.