So we are level 10, and we are pretty strong for our level (20 point buy helps here), however we are at about 50%-70% of the expected wealth by level. Most of us wanted specialty items before stat boosting items, and the big 6 in general. The result is that there are only 2 stat boosting items in the team and one (that was found not bought) was given to my cohort when I switched to a phylactery of positive channeling. It is a +2 cha headband, the other item is a +4 int headband. On top of this we haven't been investing much in weapons and armor.
This isn't really a problem per say, as we are still very powerful, but I find that the gap between expected wealth and actual wealth is widening, and while I don't need many expensive items due to my build, I can see it becoming an issue sooner or later.
Like I'd like to get mnemonic vestments and ghost bane gloves, but I have no idea when we'll get the gold for that, and maybe I'll need to instead invest in at least one stat boosting item before going for flavor pieces.
What I'd like to know is if this is something other people have noticed and if it is intentional. I mean I kind of understood this campaign was going to be a lot about exploring ruins and getting riches, so I'd expect to be above wealth by level not way under.
I'm currently playing thru this AP and am running into the exact same issue. Our party is 13th level and about halfway thru book 4. We are ahead of expected level (we are on the fast progression) by a level, but even considering we should only be 12th we are still almost 50% behind average Character Wealth. We have thus far had a character die in almost every book (not the first because the GM took pity), and raising said characters has put us even farther behind. I can only assume this was intentional, maybe to drive the party to continue exploring, but it seems to be a major flaw in this AP. It reached a point where I had to discuss adding extra treasure to our GM. Maybe you should do the same.
My party just finished chapter 2 (6th lvl) using slow advancement track and they are almost double average wealth, and I've added know extras.