Or you could just write up your spell lists on paper, then when you want to use a different spellbook, just take out the cards currently in the binder and put the cards you want in. It's not that hard, doesn't take that much time if you already know what spells to put in (I'm guessing about 5-10 min if you're not recounting sp points), and it's much less expensive.
I would hazard a guess that you would be unlikely to have to bring more than about 3-4 spellbooks to organized play (I think the optimal ratio of people per card collection in mage wars is probably currently around 2:1 for competitive gamers and 3:1 for more casual gamers, given a collection that consists of one core set and two expansions.)
And you don't need the binders for casual play. Just use them in deck form, and during the planning phase search your deck and pick two cards. If you really don't like that, you could buy more spellbook binders.
I kind of doubt that it's really necessary to have a core spell tome 3, at least it probably isn't right now. I think a lot of cards will be released again in later expansions. What I would like to see is a spell tome with all of the "mandatory" spells of a certain school. Like say an arcane spell tome that includes dispel, nullify and teleport, a war spell tome that includes harsh forge spells, a water spell tome that includes dissolve, etc.