What’s the highest perception score possible?

[Reduxist]

The Feather and Revelation subdomains boost the cleric’s perception skill significantly and Jackal Heritage can add a racial bonus to any character. On the other hand, Zohl’s final celestial obedience grants a sacred +6 bonus. There are probably more bonuses to perception via items and bonuses to wisdom, but it is admittedly a lot to go through alone.

A little help?

[Lady-J]

that depends on how many hit die you are willing to cap off this discussion at, a creature with infinite hit die can have an infinite amount of perception

[Asmodeus' Advocate]

Lady-J wrote:

That depends on how many hit die you are willing to cap off this discussion at, a creature with infinite hit die can have an infinite amount of perception.

A valid point. I'd like to add that a creature with infinite gold could also have infinite perception.

Crafting Magic Items wrote:

Skill bonus (competence) Bonus squared x 100 gp

But I imagine that you aren't seeking answers to these grand questions for purely philosophical reasons- if you could give us more context as to the PC or NPC whose perception you're boosting, we could give better advice.

[magispitt]

Should we assume a 20th level character with standard WBL and no custom items?

[Reduxist]

magispitt wrote:

Should we assume a 20th level character with standard WBL and no custom items?

That’s what I was thinking about. It wasn’t any particular build in general, but more of a thought about how high a normal player could get his perception skill.

[Potato disciple]

Perhaps a shifter is the answer - both the minor and major falcon forms grant perception bonuses.
So: shifter 15/commoner 5, with falcon minor & major forms active.
20 ranks +3 class skill +6 skill focus +4 alertness +8 competence minor form +6 racial major form +13 wisdom (18 base +2 racial +5 levels +5 inherent +6 enhancement) +6 sacred Zhols obedience = +66.

[Asmodeus' Advocate]

Don't forget skill focus, alertness, and keen senses from race.

The highest I've ever gotten level one was a half-elven Empyreal bloodline sorcerer, crossblooded with arcane.

Race- Keen Senses (+2), Skill Focus (Perception) (+3)
Familiar- Hawk (+3 in bright light (within thirty feet of dancing lights)), Alertness (+2)
Trait- Cosmopolitan (makes it a class skill)
Wisdom- 20 (+5)
Ranks and Class Skill Bonus (+4)

For a total of +19.

The bonus for being invisible while moving is +20.

[Mystic_Snowfang]

Are they mythic?

Because faffing about with a mythic inquisitor (with all their needed spells for it up) I got a +95 perception at MR10 Level 20

[Lady-J]

half elf summoner +2 racial bonus to perception
+8 racial bonus from evolution
+6 from skill focus
+4 from alertness
eagle eyes ignore up to a -5 penalty to perception due to distance
skill unlock perception makes it so you get a +1 to the perception dc per 60 feet instead of 10 feet
+2 from jackel heritage
+2 sharp senses
+1 from uncanny alertness
+10 vmc cleric for feather domain
+20 skill ranks
+8 racial from lich
+3 from familiar
+8 vigilant edolon
+6 zhols obedience
+10, 20 or 30 from item depending on how much you actually want to spend(you can afford +80 but that would be dumb)
+2 mythic alertness
mythic skill focus always can take 20
+3 class skill
+1 trait bonus
23 base wisdom(venerable)
+6 from headband
+5 from leveling
+5 from tome
+2 from lich
+6 from demon pact with demon that give +6 profane bonus
+2 from evolution
+12 from mythic

total wisdom score 61(+25)
total perception modifier 121,131 or 141 depending on the item that you bought
total perception roll 141,151 or 161(161,171 or 181 if you burn a mythic point for +20 to a wisdom based check)

[Fuzzy-Wuzzy]

Given a sufficiently lenient GM... just put all your wealth into crafting an item that gives a +132 competence bonus to Perception (price 1,742,400, cost 871,200 gp).

[Reksew_Trebla]

Just want to point out that there is a card in the Harrow Deck of Many Things that increases two stats, then swaps them. So unless you can get a +4 racial bonus to wisdom, an orc boosting strength as much as possible then drawing this card to swap with wisdom might be a better build.

[dysartes]

Fuzzy-Wuzzy wrote:

Given a sufficiently lenient GM... just put all your wealth into crafting an item that gives a +132 competence bonus to Perception (price 1,742,400, cost 871,200 gp).

While that could be amusing, one of the constraints from the OP's second post was "no custom items".

In the same vein, while it wasn't explicitly stated, I'd assume no Mythic - not sure about templates, though.

[Nord]

half-elf occultist with the Reliquarian archetype can get ridiculous amounts of perception.

To name a few bonuses:
lvl ranks in perception.
skill focus (half-elf racial).
lvl/2 implement (divination).
lvl/2 feather domain ability (gained from Reliquarian).
class skill bonus.
wisdom bonus (main stat for Reliquarian).
half-elf bonus.
alertness (from animal companion).
Just from these bonuses alone it would be around 56 at lvl 20. Add a trait and some magical items on top of this.