All right, so it looks like I can't just toss out a number. Time to research the closest existing magic items.

I think, if I were buying published items to fulfill this function, I'd go with these:
  • Schema of Restoration: 11,200 gp (schema) + 5,000 gp (material component)
  • Schema of Panacea 11,200 gp
  • Schema of Neutralize Poison: 6,000 gp
  • Schema of Remove Curse: 6,000 gp



So that comes out to 39,400 gp.

Each of those would have 1 charge per day. But the proposed rod would share 1 charge per day between all effects. So I feel like there should be some sort of cost discount for that.

Schemas can only be used by casters. But I feel like any party is going to have someone who can activate these. And they're mostly out-of-combat effects, so you're not really gaining action economy by increasing the number of party members who could use it.

Going with my second version, the rod would only be able to duplicate part of Restoration for a single charge. You'd have to choose between negative levels, ability drain, or ability damage instead of doing all 3. I feel like that should warrant some kind of discount too.

My second version also completely leaves out arguably the most powerful effect of Restoration, recovering lost levels.

I suppose I could cut the cost in half by making it take up a body slot. It wouldn't really change the usefulness of the item though. It's intended for out of combat use. And when you're not actively fighting something, temporarily switching out a ring (or whatever) is no big deal.