A while back I was doing a survival game with trading elements and I wanted an idea of all the various items and categories there were across several games. So I took a half dozen games in the genre, and basically dumped their entire inventory contents to look at commonalities.
Hundreds and hundreds of items, resources, and so on.
I don't know if it would be of use to you, but if you're interested I'll post it for you to peruse while you continue to design your own item system Adam.