I have searched but found no definite answer.
Also is the rule in pathfinder different from 3.5?
I think the idea is to figure out the CR of the creature, then use that as its level, and check the chart under step 6 here:
http://paizo.com/pathfinderRPG/prd/creatingNPCs.html
Or you can give it the wealth of a PC (once again using CR as level) which adds 1 to the CR of the creature.
And as always, use common sense, and GM judgment to figure out what is right for your game.
Note also:
"Encounters against NPCs typically award three times the treasure a monster-based encounter awards, due to NPC gear.
To compensate, make sure the PCs face off against a pair of additional encounters that award little in the way of treasure. Animals, plants, constructs, mindless undead, oozes, and traps are great “low treasure” encounters. Alternatively, if the PCs face a number of creatures with little or no treasure, they should have the opportunity to acquire a number of significantly more valuable objects sometime in the near future to make up for the imbalance.
EDIT: Found it!
Bottom of this page:
http://paizo.com/pathfinderRPG/prd/monsters/monsterAdvancement.html
"A monster with class levels always possesses treasure equal to an NPC of a level equal to the monster's final CR (as calculated in Step 3, below). To determine the value of this gear, use the value listed for a heroic NPC of that CR, as listed in Table: NPC Gear. Once a total GP value is determined, follow the rules for outfitting an NPC as outlined in that section. Gear should help a monster with class levels remain challenging and retain statistics close to those presented on Table 1-1: Monster Statistics by CR.
Step 3: Determine CR
Determining the final CR for a creature with class levels requires careful consideration. While adding a class level to a monster that stacks with its existing abilities and role generally adds 1 to its CR for each level taken, adding classes that do not stack is more complicated.
Table: Monsters with Class Levels gives general guidelines regarding which core classes add directly to a monster's abilities based on its role. Classes that are marked “key” generally add 1 to a creature's CR for each level added. Classes marked with a “—” increase a creature's CR by 1 for every 2 class levels added until the number of levels added are equal to (or exceed) the creature's original CR, at which point they are treated as “key” levels (adding 1 to the creature's CR for each level added). Creatures that fall into multiple roles treat a class as key if either of its roles treat the class as key. Note that levels in NPC classes are never considered key.
Very thorough explanation. Was this ( A monster with class levels always possesses treasure equal to an NPC of a level equal to the monster's final CR (as calculated in Step 3, below). To determine the value of this gear, use the value listed for a heroic NPC of that CR, as listed in Table: NPC Gear. Once a total GP value is determined, follow the rules for outfitting an NPC as outlined in that section.). ever mentioned in 3.5?