I'd hate to be a PC facing something with a modifier over +20.
Are there many examples of a high initiative dictating the course of the fight? I mean, as someone said, a high initiative only lets you go 1st one time (or perhaps twice, with a surprise round). Additionally, you can refocus to go first in any given round.
The biggest advantage/abuse seems to be for rogues, for getting in all those sneak-before-they've-acted hits in. But certainly we can agree there are diminishing returns?
I mean isn't anything above +20 initiative excessive?
I am partly playing devil's advocate, because I read Jester's storyhour and have seen how high initiative can sometimes dictate a fight, at high levels. Of course, in most of those examples the baddie would have done some damage (which would be healed by Horbin the MFKG Holy) and died just as painfully fast.
I suggest:
Ring of Surprise
While wearing this ring you gain a +5 competence bonus to initiative. Additionally you may always act in a suprise round. However, if you would not normally be able to (by failing spot/listen checks), you must act last regardless of your initiative (you act normally after the suprise round).
[Strong Divination, Minor Artifact (~100,000 gp)
for high level games. 100,000 gold isn't chump change, but neither is guaranteeing youll never be 'surprised'. I used the bonus squared x 2,000 and assigned the 'never-suprised' ability 25,000 cost (doubled for being a secondary power on a ring).
Bandit Bandanna
Wearing this bandanna confers a +1-4 competence bonus to initiative. This bonus is lost if you are denied your dexterity bonus (except during the first round of an encounter).
Moderate Transmutation,
Fox's Cunning; Market Price: +1 (1,000 gp), +2 (4,000 gp), +3 (9,000 gp), +4 (16,000 gp).
would be better for lower level games.