So, I posted this when this thread started, and I'm not sure if people just thought it was crap, or if it got lost in the shuffle...
Since I have a relatively high opinion of my own ideas, I figure it got lost and I'll repost it ;-)
Thoughts?
You get X number of items that you can use, and then the first time you purchase a 1st, 5th, & 9th level spell (of each school, so people who dual school get more of a benefit) it increases X by one. Not +1 for each spell of that level, just for the first one. You can probably throw in an increase of 1 per Y formal levels
Rituals cast directly on your spirit don't count, but spirit linked items do. (Essentially making your spirit a "free" item.) Spirit linked items also automatically count against you.
Originally, X started as 5, but more because I thought it was a good starting point, as 3 seemed to low, and 10 seemed to high. 5 seems like a happy medium to me. I could also see giving the bonus out at 3, 6 & 9 (more beneficial to "real" casters, as opposed to "cast from scroll guy"
When you go through logistics you pick out the appropriate number of items that you want to be able to use for that logistics period, and you can switch them out at the next one.
These items can still be stolen, but can't be used by the person who steals them until the next logistics.
If you find an item, you can use it after the next time you go through logistics. Though a possible alternative to this is that an appropriately aspected permanent (or limited) COP can allow you to "attune" to an item, but only if you have a free slot for it, the circle will not allow you to swap out items.