How many Search skill ranks are needed for ...

[Kinnio]

How many Search skill ranks are needed for Secret (Hidden) Doors in end-game, non-epic dungeons?

I do not do traps

[Anneliese]

while this does not answer your question per se - it is very easy to get detect secret door or true seeing at higher levels.

Or in other words - the search skill is sort of useless unless you use it to find and disable traps (for which you need at least 1 rogue level)

[Mercureal]

Hard to say - secret doors generally have lower DCs than traps, which in higher level quests are in the 40s. On the other hand, I can't remember too many secret doors in higher level quests...

[nerdychaz]

If all you are after is doors, use a clicky (found on many items) of detect secret doors, or if you are arcane and/or use UMD skill, wands.