I have tried to find out the cost of the following item:
An item that have the same properties as the Magic staff list, Staff Spell I (Spell nr. 3).
Basically, you'll have to research a new spell to do that, since Staff Spell only lets a user store spell specifically in his personal staff. So you'll have to create a new version of the spell (probably higher in level) that let you store the spell in any item. Then you'll haven to imbed the spell into the object and make the power constant.
Hmm... sounds pretty expensive and time-consuming!
For a cheaper and simpler alternative, you could simply create a daily item of Staff Spell I (but then you'll still need a personal staff to store your spell into).
Is it correct that you don't need an SCSM when you cast the spell in the staff?
No, you'll still have to cast the spell normally to store it in the staff. Actually, you'll have to cast it within one minute (6 rounds) after casting Spell Staff I. Later, you'll be able to "release" the spell without casting it again.
Spell Staff is already broken as it is, no need of making it even more powerful