To create a magic staff, a character needs a supply of materials, the most obvious being a staff or the pieces of the staff to be assembled.
The materials cost is subsumed in the cost of creation: 400 gp × the level of the highest-level spell × the level of the caster, plus 75% of the value of the next most costly ability (300 gp × the level of the spell × the level of the caster), plus 1/2 the value of any other abilities (200 gp × the level of the spell × the level of the caster). Staves are always fully charged (10 charges) when created.
If desired, a spell can be placed into the staff at less than the normal cost, but then activating that particular spell drains additional charges from the staff. Divide the cost of the spell by the number of charges it consumes to determine its final price. Note that this does not change the order in which the spells are priced (the highest level spell is still priced first, even if it requires more than one charge to activate). The caster level of all spells in a staff must be the same, and no staff can have a caster level of less than 8th, even if all the spells in the staff are low-level spells.
The creator must have prepared the spells to be stored (or must know the spells, in the case of a sorcerer or bard) and must provide any focus the spells require as well as material component costs sufficient to activate the spell 50 times (divide this amount by the number of charges one use of the spell expends). Material components are consumed when he begins working, but focuses are not. (A focus used in creating a staff can be reused.) The act of working on the staff triggers the prepared spells, making them unavailable for casting during each day of the staff 's creation. (That is, those spell slots are expended from the caster's currently prepared spells, just as if they had been cast.)
Creating a few staves may entail other prerequisites beyond spellcasting. See the individual descriptions for details.
Crafting a staff requires 1 day for each 1,000 gp of the base price.
When creating a stave, the cost for the material components is calculated before of after "the number of charge used" part?
Let's say I am making a staff that cast stoneskin as its first spell, with a material component of "(granite and diamond dust worth 250 gp)".
If the stoneskin spell drain 1 charge the price is:
SL 4, CL 7 4*7*400= 11.200
If the stonesking spell drain 2 charges for each use, the staff would cost (4*7*400+250*50)/2= 11.850
Following the pricing guidelines above I think that the second procedure is the right one, but reverse engineering a staff of life show that it has been priced using the first procedure.
(The explanation on how to price the material cost part is after the "charge used" reduction)
Reverse engineering a staff of life
SL 6 SL 11 = 6*11*400= 26.400
SL 5 CL 11 = 5*11*300= 16.500
Material component 50*5.000 = 250.000
266.500/5 = 53.300
Total creation cost 79.700 Market price 109.400