Help pricing this kind of magic item

[Eladrinblade]

I use a homebrew system where all casters have spell points and spontaneously cast from known spells. Wizards don't have spellbooks; spellbooks aren't a thing. I want them to be, and I had an idea for how to do it: charges/day spell completion items (and I could combine several together using the standard rules for that in the DMG), but I have no good starting point on how to price it.

A use-activated/continuous item costs 80 times more than an equivalent scroll, before adjusting for spell duration. A charges/day item costs less than that, but how much should the "spell completion" part take off?

[InvisibleBison]

I'd say a 30% reduction, as per the rules on restricting an item to members of a single class, is a good starting point. If only wizards can use these items, that seems sufficient. If anyone with the spell on their spell list can use it, you might want to reduce the discount a bit. Maybe by 5 percentage points for each additional class that can use the item, to a minimum of 10%?

[Eladrinblade]

I'd say a 30% reduction, as per the rules on restricting an item to members of a single class, is a good starting point. If only wizards can use these items, that seems sufficient. If anyone with the spell on their spell list can use it, you might want to reduce the discount a bit. Maybe by 5 percentage points for each additional class that can use the item, to a minimum of 10%?

Good idea. I went and found where that rule comes from; turns out I've never read that sidebar before.

[jmax]

I use a homebrew system where all casters have spell points and spontaneously cast from known spells. Wizards don't have spellbooks; spellbooks aren't a thing. I want them to be, and I had an idea for how to do it: charges/day spell completion items (and I could combine several together using the standard rules for that in the DMG), but I have no good starting point on how to price it.

A use-activated/continuous item costs 80 times more than an equivalent scroll, before adjusting for spell duration. A charges/day item costs less than that, but how much should the "spell completion" part take off?

There are already two items that do this in different ways.

1) Eternal Wands (Magic Item Compendium p159)
2) Runestaffs (Magic Item Compendium p224)

Eternal Wands use command words to cast a specific spell X times per day. They are priced like command word items: 360*SL*CL*Uses_Per_Day (max *5 for unlimited uses). The default uses per day is 2. Stack a bunch of them on top of each other and call it a book.
Any character can use an Eternal Wand, and they use minimum ability score modifier and caster level. However, single-spell staffs are priced the same as wands with the exception of having a minimum caster level of 8, so you could perhaps reasonably allow for an "Eternal Staff" concept (never mind that this is going to be book form) that sets the caster level at 8 unless the user's caster level is higher (ditto for the ability score for save DCs). Knock off 30% for it being wizard only.

Runestaffs are interesting in that they use your own spell slots. In your game, it'll be using your own Spell Points instead. Aside from that and having a fixed number of users per day per spell, they work like staffs, using your caster level and ability scores (there's no "whichever is better" because you can't activate them if you can't cast a spell of the appropriate level). Runestaffs can hold multiple spells and are priced at 100*(1+Uses_per_day)*SL2 for the highest-level spell and 50*(1+Uses_per_day)*SL2 for subsequent spells. They're already priced with the expectation of use from a specific class, so don't knock off the 30%.

If you want the spellbooks to increase the available number of spells per day, go with the Eternal Wand model. If you want them to draw from the same resource pool as the PCs' spells, go with the Runestaff model. If you want the Runestaff model without the limited uses per day per spell (since, after all, it's drawing from a finite resource pool already), it would be reasonable to price it out as 5 uses per day for everything, which would be the equivalent of unlimited use for other types of items. If you want limited uses per day but a large pool of those uses instead of one per spell, just do something hand-wavy like adding up the total number of spell-level-uses and calling that a pool of points you can use from the book, spending X points to cast an X-level spell. It's probably not perfect mathematically, but it should be close enough.

Incidentally, why don't the D&D books just price things out with equations? The word-problem-format descriptions are very inefficient. It's still algebra either way, and the contortions to avoid actual equations really seem to get in the way. /rant

[Eladrinblade]

Runestaves seem like almost exactly what I was going for.