Update in turn: After literally months of sporadic searching, I *finally* found a storage box that suits Mage Wars about as close to perfectly as I can reasonably expect:
Plano 23731-01 Stowaway Deep Open Compartment
http://www.planomolding.com/product.php?BCCID=138&PID=753It's basically an open-compartment tacklebox, that almost perfectly fits two spellbooks side by side. It can hold up to six, or 4 or 5 with tokens, dice and cards from the Portability Project. Fits well in a backpack, all is good. Costs less than $10 at Amazon, as well.
With the corner and condition cards printed and sleeved, I will probably never need to open that godawful oversized Mage Wars box again! ; )
One of the things I'm really happy about is that I've got two of these now: one to hold four starter spellbooks and the things I'll need to teach Mage Wars, and another to hold my predesigned spellbooks and all the things needed to play anytime, anywhere. So if I think I'll have an opportunity to infect other gamers with the Mage Wars virus (heh), I can just grab the tote and go.