Thinking about the multiple spells books...
The "Blessed Book" seems to have an error in the description. It says in the SRD that "A wizard can fill the 1,000 pages of a blessed book with spells without paying the 25 gp per page material cost." But then in the magic overview section, it says that "Materials for writing the spell cost 100 gp per page."
If the Blessed Book is intended to completely eliminate the scribing cost, then it is something every wizard should pick up, because it costs 12500 and would save you over 50000 in scribing costs. If it is intended to just provide a 25gp per page discount, then it is still worth it, depending on when in his career the wizard can get one. At that price, scribing more than 500 pages into the book would make it worthwhile, so the wizard would need to get the book early enough in his career to make that likely. (Of course, the convenience of having only one book to lug around would add to its value.)
This math also does not consider the possible spell-trading that was mentioned above, and also does not consider the value of any captured spellbooks, which eliminate 50gp per spell level of costs.
If there is interest, I will run the math for a higher-level starting PC wizard as well, because their starting money is so much higher than an NPC, so they should have even more spells (although, if I were playing a starting mid-level PC, I might just use these numbers and spend more of my gold on items.)