I believe it's well established on these forums that I come from a bit of a new school background. I never really started playing in a big way until 3.5, and my biggest campaigns I've run/played in before ACKs were 4e and pathfinder.
So it was always a bit shocking to me that magic Staves in this game are either glorified wands, with limited charges that will eventually run out permanently, or infinite usage items. To me, staves were always something that would have a smaller number of charges than a wand, but which would require the caster to be high enough level to cast spells into the staff to recharge it.
As it stands, staves (at least new ones players might want to create) seem to have little to differentiate them from wands. Now, as an older, wiser gamer, I now understand that the 3 or 4 days a mage might have to dedicate to recharging a staff are meaningless in the grand scheme of things, so i'm trying to think up a way where recharging a staff can be possible, preferable to just making a new one, and yet represent a true tradeoff of costs in some form.
So my thought is this:
* Adding a charge is a magic research project.
* You must choose a spell on the staff and be able to cast it.
* The difficulty is increased by one half the spell level of the highest level on the staff, regardless of how many charges it uses.
* The cost is equal to half the base cost of the spell you chose. No special components are required.
* You must have a laboratory with sufficient value to create potions or scrolls of the spell you're using (so 4000gp for level 1, etc.)
* For every 10,000gp above the value of the highest spell on the staff, +1 to your research roll, not exceeding the total value of the staff when it was created.
* Recharging takes 1 day per spell level of the spell being used to recharge.
* If you succeed, you add charges equal to the number of charges required to cast that spell.
* For every 5 points more you beat your target roll by, add 1 additional charge, regardless of how many charges the spell itself added.
So I like this because it still represents a cost, there is some risk of failure involved, especially for low level mages who were fortunate enough to find a staff. Yet higher level mages can more easily recharge, but even a high level mage may find themselves spending a week or more of downtime to recharge a fully spent staff. 1 day per spell level might be too generous, but ideally it should be some number less than 1 week so that recharging a staff is preferable to making a new scroll (since scrolls can be created earlier, are easier to give out, and can be of any spell rather than just the spells on the staff).