It's been long-established that I'm not a big fan of clerics, and that I kind of like the NetHack approach of "make sacrifices, pray to diety, hope for not-smiting", which anybody should be able to do. I was also considering that old-school polytheistic deities typically expected material sacrifices in return for their aid, instead of just prayer and devotion.
Well, we have these divine spellcasting prices in the Equipment chapter...
So what if instead of having a cleric at all, before you set out for the dungeon you'd do the old "I go to the temple, sacrifice ten goats, and pray to Tyr for courage in the coming expedition to retrieve the Whatsit of Blarg." Now, a goat, he is 3 gold pieces. A casting of Remove Fear is 10 gold pieces. So later, when you're out in the field and the party gets ambushed by mummies and you call on Tyr to lift the fear-paralysis and avoid TPK, you have (depending on the exchange ratio between "goats now" and "casting credit later", and maybe contingent on a deific reaction roll) maybe one, maybe three castings of Remove Fear.
It's super-duper vancian. This is preparing spells once for the entire adventure (you know, like you were supposed to do back in OD&D but everyone has forgotten). There are obviously some wrinkles, like not letting people buy RL&Ls to use in the field (and "spell selection" more generally). Maybe taking oaths opens up higher level spells (from a particular deity, while walling off other deities)? Healing in general is kind of weird - I could definitely see adding a spell for this that gives you an extra level of Healing proficiency for n minutes, so you pray for that and then do your healing. Maybe sacrificing to improve State of Soul makes sense (and then it applies a bonus when your buddies bring your corpse back to the temple, where the ritual magic happens). People buying up enormous piles of spells might be an issue, but could maybe be counterbalanced by having preparation take time? Ritually sacrificing 10 goats with all the proper ceremony is not something you want to rush, and something like sacrificing a hecatomb of oxen for Control Weather is more than one day's work. There's also the cost disparity between potions and spellcasting (potions don't go bad if you don't use them this adventure, though).
Anyway, something to kick around.