I've got the sources and ideas for the Items laid out. What I need help with is giving them in-game stats. It seems like every IoP I put together is either a SotC knockoff or just a route to give the character access to Sponsored Magic. I want these IoPs to be unique, rather than just a way to get around on the limit of three SotCs.
What powers or abilities do you want the players to have/get from the IoP? Once you've figured that out, then you just need to find an item that would have some form of appropriate tie-in with the power.
A spoiler example from Changes:
Harry's mother Maggie Dresden's pentacle with gemstone: The ability it provides seems to be equal to the power: World Walker, thus qualifying as an IoP.
If you can give us an idea of what you'd like the player(s) to be able to do, then we might be able to suggest an item.