It sure is, but Book of Geometry is free. When you get a Headband of Int +6, then you can start saving gold for BBB.Actually, how does that work?
BBB costs 12.500 gp and has 1000 pages. Meaning that it costs 12.5gp per page. So you'd need to write spells of level 8 and higher to save money using the Book of Geometry, which still makes BBB better.
Forget the fatespinner, get Archmage. Prerequisites are harsh, but worth it. +1 Spell Power, Mastery of Shaping, and Spell-Like Ability (taking one of 9th lvl pays of tremendously, say Time Stop) are a must.finishing off with either Fatespinner or Archmage levels
From my experience (and I've been playing a Batman Wizard for a year and a half now), the main problem is - the party. There're 6 of us + animal companion, and I can rarely cast area spells since we're usually fighting smaller number of enemies and once the party swarms them anything with a radius bigger then 10' becomes obsolete.
That's where Mastery of Shaping comes in, so you should get it as soon as you can.