Can't you use other nonfeat cost reduction to make that BBB cheaper? Like making it x class only.
Um... it can require a DC... 15? ...21? spellcraft, or ...forgery, check to scribe... that knocks off 10% (~350gp), But I can't see a way to get a 'specific class' (and alignment is
right out!) requirement in there well (which could knock off 30%) Unless they meant a class feature (such as arcane casting) in which case, the book only functions for those who prepare and scribe spells as a wizard does... if I could do that it would get it to 2214gp.
The Spellcraft skill lets you memorize spells from another person's spellbook. The DC is 15 + spell level for each spell, one check per day. IIRC, Complete Arcane lets you permanently work from someone else's spellbook with a DC 25 + spell level Spellcraft check, too. It's a little unreliable without a high Spellcraft modifier, but it should help cut down costs for having large numbers of spellcasters around.
So sharing the BBB could be good... I'd not reread the entry, just got the price and linked it; it's 1000 pages, not 100 (I'd misremembered that instead of 1k pages, that each spell took 1 page in the book) so the cost of unique arcane spells is 3.5gp (or 2.2gp) per spell level. Who all has need of a spellbook, and of those who's got the lowest spellcraft? I'd need to get +21 to permanently use the BBB with 6th level spells I'd not scribed myself.
And though the DC to prepare from it is only 15+level, the DC to decipher is 20+spell level, and deciphering must be done first. However it says "A read magic spell automatically deciphers a magical writing without a skill check. If the person who created the magical writing is on hand to help the reader, success is also automatic." so if anyone else needs to decipher my cohorts handwriting just ask
So the BBB can be shared with only +11 to spellcraft (my cohort can only get to 6th level spells, so unless someone else needs to get higher, the DC is 21, and you can take 10 on spellcraft). Anyone's character/cohort gonna have less that that on spellcraft?