What about “cost of attendance at the state flagship for the state/s that the student is a resident of”?
Also, make sure you’re fair:
you can tell your daughter that you promise you’ll engage the same percentage of income for her as for her step/half siblings, and even more since your business has failed.
It’s very important, for your daughter’s sake, that she understand there’s no “favorite” between your three children, all three will get an equivalent financial effort from you.
One issue though is that, although YOU don’t make money, your wife probably does, and your ex wife may consider that either 1° you sold your business to escape your financial responsibilities toward your daughter’s college, or 2° if you’re living off your wife’s wages, then she’s glad to make her pay.