I certainly wouldn't 'force' my players to spend their money in any certain way, which is what this boils down to if you reduce their wealth by level.
What I could see doing is giving them 'seed money' from the temple to spend as a group (you are looking at 1000 gp) and the ability to buy potions from the temple at cost. Let the group decide how they want to spend it and on what.
Generally in games I run a play with, the party puts some of their loot aside for this sort of purpose anyway, and it works pretty well. Even more then raw hit point healing, they will also probably need to deal with condition removal (although being allied with a temple probably means that they can get 'next day' healing of that sort.)
You could also consider tweaking the celebrity perks social talent to provide access to free healing spellcasting services. Or maybe if the group combines their celebrity perks, they can get a potion for free 1/day as long as they have fewer than X potions (where X is a number you pick, and you might not need it if the action is too fast-paced for them to stockpile hundreds of potions on off-days).
Let them buy wands of cure light wounds for cost and UMD them, it's much more efficient. Make sure they know that at least one of them should be good at UMD. Maybe let them buy a Wand Key Ring for CLW at cost too, but they probably won't need it if somebody has high Cha, and they'll want the UMD anyway for, say, a wand of lesser restoration (which you might also let them buy from the temple at cost).