The cost for a Orange Ioun Stone is 30,000gp. Since this is a no slot item, if you were to make a ring or other magic item that used a body slot that gave +1 Caster level, the cost would be 15,000gp. What is the fomula to determine the cost of the bonus caster level? I would think that it would be either (bonus caster level squared) x 15,000gp OR (caster level bonus) x 15,000. I would believe either, as the bonus to caster level is a pretty nice enchancement for a caster as it affects damage, duration, concentration checks, and bonus to beat SR, amongst other things. But since it doesn't give bonus spells or higher level spell slots as I understand it, I don't know it it would merit the higher cost.
Has anybody seen a ruling on this anywhere? I have looked a bit, but not found much of anything ont he subject.