Mark confirmed that wands have 50 charges and they take 1 resonance use in the Playtest Reveals from the Crypt of the Everflame with GCP Finale!! thread.
http://paizo.com/threads/rzs2v6zz&page=1?Playtest-Reveals-from-the-Cryp t-of-the
In other news, he also confirmed that anything that was an x uses/day item is now just a straight resonance cost. I think we already knew this, but good to get it spelled out. Also, that scrolls and other consumables use up the consumable and cost 1 resonance.
I think most people are fairly happy with the consumable aspect (price structure aside), but the wand reveal was met with some dismay. There had been a lot of people that had assumed that charged items were a thing of the past. I would be quite happy to see the end of them as well.
Every right thinking person would agree that being able to obtain a wand with a spell appropriate for your level (level 4 spell, at character level 7, for example) and costing only 1 resonance to cast would be game breaking. Even if you had 50 charges of it, given how few spells you get now, would be very strong.
So, I think it would be worthwhile to discuss any ideas that would remove charges from wands, yet still keep them balanced with prepared spells. Also, I would also like to add that I am a fan of resonance for magical items worn, consumables used and activating magic items, but it needs play testing and maybe refinement.
OPTION 1
Cost and wealth by level (WBL) is the first thing that comes to mind. In PFe1 such a wand (4th level) would be 90% of your total WBL (23,500gp @ 7), very unlikely that you would not have access to it. If WBL scales in a similar way to PFe1, then it almost doubles every 2 levels, which means that at level 9, you could spend half our resources and get a level 4 wand. That seems too good.
Balance through cost alone seems difficult. There would be a very fine line between so expensive that they are no obtainable, not very useless because they are too low level, or too good because they are potent and spamable.
OPTION 2
Part cost, but also increased resonance spend. So, one idea I had was maybe wands could be moderately expensive, say investing 25-40% of your silver (similar amounts that martial will spend on their primary weapon) for a wand with a spell that is 1 level behind your top level spells. However, it cost 3 points of resonance to cast from. This means using a wand is a big dump of resonance, but it is a fairly powerful spell. This means you cannot spam it, but you might use it 2 or 3 times a day, and that use should feel powerful and useful. This definitely makes spending resonance an interesting decision. Do I want more magic items, do I want more standard consumables, or do I want to run lean on those and really have a few wand charges to throw around?
Additionally, so that lower wands are more useful, there should be a resonance discount for low level wands. Maybe if it is 3 levels below your max it is 2 resonance, in if it is 5 levels below it is just 1.
I think I like this option better.
BUT I WANT TO THROW CASH AT MONSTERS NOT REASONANCE
So, I have thought of an addition option that helps move away from charged items, but still allows power through consumable items. Maybe there can be a bulk crafting discount for making 10 identical scrolls in one batch. Perhaps a 20% discount. That way, there are not charged items exactly, but scrolls pick up the slack as spamable a consumable. It is kind of a halfway house. Maybe.
STAVES
I really hope staves (staffs?) are not spells on a stick, but rather the caster equivalent of magic weapons. +1 to hit with spells, +1 DCs. Since +1 armour increases saves and TAC (I think?), shouldn't there be an items that allows casters to keep up?