‘ "Implement a way to sell items for gold and mana" This is dumb, as you can make items infinite. ‘
Calling an idea dumb is not the way to engage in discussion, it gives the impression you are only interested in being insulting rather than improving the game.
As to the actual point, infinite items can be changed.
Expanded suggestion: Remove the current infinite items system. Add the option to dismantle items for gold and mana. Once you have dismantled enough of a specific item you get a blueprint that allows you to spend gold and mana to make new ones.