Instead of an item, how about substituting rituals, instead? Maybe they require a feat to take, but when you do a ritual, you may expend XP equivalent to the XP cost for making the buff item in question, to obtain the bonus. Call it a Ritual bonus, so that it can continue to stack with Inherent bonuses.
Thus, people can get the bonuses, but instead of a friendly wizard making an item, they have to invest the XP themselves....
Thus, people can get the bonuses, but instead of a friendly wizard making an item, they have to invest the XP themselves....