For the calendar year 7/1/2008 -- 6/30/2009, the Big 12 distributed $121,192,164 to its 12 members. Oklahoma received the most, $12,209,800, and Kansas State received the least, $8,374,959. If they had split the revenue equally, every school would have received $10,099,347. The unequal split "cost" Kansas State $1,724,388. The way the money is split has very little to do with the difference in revenues. Missouri received $10,449,437 and Kansas received $11,494,441, so they would have actually made less with an equal split.
Guidestar.org has copies of the form 990s that nonprofits have to file with the IRS. You can confirm these numbers by looking at the Big 12's.
I actually think that those teams joining the Big East is a legitimate possibility, but not for the reasons you claim.