Hmm. I can answer this, I think. I just had to do a lot of this for some NPCs my players hired. There are two systems I know of.
First, the DMG. On page 135 there is a "wealth by level" table for PCs... but on page 127 is the lesser-known wealth table for NPCs. They have less loot. In addition, the pages leading up to that table show examples of the kinds of gear such NPCs would have, and that's by level too. It really helps to get a flavor for how to do it.
I mostly follow those tables, but I never have them carrying around as much gold as the tables suggest. If they say that a typical 3rd-level character would have some masterwork equipment and 1500 gp cash money, I spend that 1500 gp and better protect them.
I do this because hirelings are game-breaking and economy-breaking. If your party is evil enough, they can hire a henchman for 3 gold, kill him away from town, and make an easy 2000 gp. So for me I have those NPCs spend that extra gold on things like a reserved just-in-case fund for body retrieval if dead. Or, a 1-charge wand that contains an escape spell. You know,
some kind of contingency to offset the hire-moneybags-one-at-time-and-ambush-them-in-an-alley problem.
There is a second option. The Magic Item Compendium presents a revised method for determining what NPCs have. Page 227. This method is essentially a list of magic items at various levels of power. For example, a 5th-level NPC would have three items at power levels: 5, 4, and 3. These items have set ranges of power, listed on page 226. So for our 5th-level NPC, he might have a brooch of shielding, +1 chain armor, and a potion of Cure Serious Wounds.
Personally, I like the DMG way better. But this is your call. Good luck.
EDIT: crap. I just re-read your post and it appears that you do know the wealth-by-level tables. Instead, I guess you were asking if a 9th-level cleric should have a different amount of wealth than a 9th-level adept. I would say yes. And I would probably do multiple levels of downgrading. Maybe like this:
aristocrat: wealth by level as normal
adept/expert/warrior: wealth by level - 1
commoner: wealth by level - 2
PLUS, if the NPC has non-elite stats (or worse!) then I would knock off an additional level. So a 3rd-level commoner with non-elite stats would be the equivalent of a 0-level PC. In other words, basically no money.
A 1st-level commoner with non-elite stats would have a wealth level of -2, or probably in debt. I'm thinking of kids just starting out in life and with their first credit card already maxed out.

Or a farmer who bought land on a loan and will spend the rest of his life toiling to pay it off.