OneFiercePuppy: I don't know how many spellbooks there are of each spell. I'd like to do a party with two 4-book Bishops. Are there enough spellbooks for me to get good end-game results, assuming I'm patient enough to simultaneously develop two Bishops?
Almost every spellbook in the game can be purchased from an NPC, and getting money to purchase them is easy with Alchemy.
The exceptions are as follows:
*: Holy Water, which is only available as a rare drop from two unique creatures, one of whom is an NPC you don't want to kill
*: Mind Stab, which isn't obtainable in the game at all (outside of things like save editors)
Note that the only spell above 5th level with a spellbook is Banish.