The cracked dusty rose prism ioun stone from Pathfinder Campaign Setting: Seekers of Secrets (2009) costs 500 gp, and grants a +1 competence bonus to initiative. It really gets on my nerve that this item, from a PFS-centric book in 2009 in a larger section on ioun stones, is now a virtually standard buy for adventurers. I can understand items like the ring of protection, cloak of resistance, and so forth being commonplace, but does every adventurer really walk around with a cracked ioun stone?
As an alternative for my homebrew campaign, I'm thinking of making a slotted item that provides the same thing, a competence bonus to initiative checks. If a slotless +1 bonus is 500 gp, I figure a version that takes up a slot should be 250 gp for a +1 bonus, 1000 gp for a +2 bonus, and generally 250x^2 gp for a +x competence bonus to initiative.
Does this sound reasonable? Furthermore, what slot should it be? I'm thinking shoulders slot, or maybe neck slot. Definitely should be one of the good ones.
Cape of the Action Hero: Takes up the cloak slot. It gives a +1 competence bonus to initiative. Many GMs are replacing items of abilities with additional points per level, look into it.
I'm not really interested in changing the game mechanics, I'm just trying to tell whether a new item should be made more expensive, really.
The fact that it's such an auto-buy is a heavy indication it's too cheap anyway (and in this case, it sure is).
I'd slot it the same as circlets, and price it at 500 * bonus ^ 2, despite being slotted.